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10 <title>Debian Policy Manual</title>
11 <author><qref id="authors">The Debian Policy Mailing List</qref></author>
12 <version>version &version;, &date;</version>
15 This manual describes the policy requirements for the Debian
16 GNU/Linux distribution. This includes the structure and
17 contents of the Debian archive and several design issues of
18 the operating system, as well as technical requirements that
19 each package must satisfy to be included in the distribution.
24 Copyright © 1996,1997,1998 Ian Jackson
25 and Christian Schwarz.
28 This manual is free software; you may redistribute it and/or
29 modify it under the terms of the GNU General Public License
30 as published by the Free Software Foundation; either version
31 2, or (at your option) any later version.
35 This is distributed in the hope that it will be useful, but
36 <em>without any warranty</em>; without even the implied
37 warranty of merchantability or fitness for a particular
38 purpose. See the GNU General Public License for more
43 A copy of the GNU General Public License is available as
44 <file>/usr/share/common-licenses/GPL</file> in the Debian GNU/Linux
45 distribution or on the World Wide Web at
46 <url id="http://www.gnu.org/copyleft/gpl.html"
47 name="the GNU General Public Licence">. You can also
48 obtain it by writing to the Free Software Foundation, Inc.,
49 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
57 <heading>About this manual</heading>
59 <heading>Scope</heading>
61 This manual describes the policy requirements for the Debian
62 GNU/Linux distribution. This includes the structure and
63 contents of the Debian archive and several design issues of the
64 operating system, as well as technical requirements that
65 each package must satisfy to be included in the
70 This manual also describes Debian policy as it relates to
71 creating Debian packages. It is not a tutorial on how to build
72 packages, nor is it exhaustive where it comes to describing
73 the behavior of the packaging system. Instead, this manual
74 attempts to define the interface to the package management
75 system that the developers have to be conversant with.<footnote>
77 Informally, the criteria used for inclusion is that the
78 material meet one of the following requirements:
79 <taglist compact="compact">
80 <tag>Standard interfaces</tag>
83 The material presented represents an interface to
84 the packaging system that is mandated for use, and
85 is used by, a significant number of packages, and
86 therefore should not be changed without peer
87 review. Package maintainers can then rely on this
88 interfaces not changing, and the package
89 management software authors need to ensure
90 compatibility with these interface
91 definitions. (Control file and changelog file
92 formats are examples.)
95 <tag>Chosen Convention</tag>
98 If there are a number of technically viable choices
99 that can be made, but one needs to select one of
100 these options for inter-operability. The version
101 number format is one example.
105 Please note that these are not mutually exclusive;
106 selected conventions often become parts of standard
113 The footnotes present in this manual are
114 merely informative, and are not part of Debian policy itself.
118 The appendices to this manual are not necessarily normative,
119 either. Please see <ref id="pkg-scope"> for more information.
123 In the normative part of this manual,
124 the words <em>must</em>, <em>should</em> and
125 <em>may</em>, and the adjectives <em>required</em>,
126 <em>recommended</em> and <em>optional</em>, are used to
127 distinguish the significance of the various guidelines in
128 this policy document. Packages that do not conform to the
129 guidelines denoted by <em>must</em> (or <em>required</em>)
130 will generally not be considered acceptable for the Debian
131 distribution. Non-conformance with guidelines denoted by
132 <em>should</em> (or <em>recommended</em>) will generally be
133 considered a bug, but will not necessarily render a package
134 unsuitable for distribution. Guidelines denoted by
135 <em>may</em> (or <em>optional</em>) are truly optional and
136 adherence is left to the maintainer's discretion.
139 These classifications are roughly equivalent to the bug
140 severities <em>serious</em> (for <em>must</em> or
141 <em>required</em> directive violations), <em>minor</em>,
142 <em>normal</em> or <em>important</em>
143 (for <em>should</em> or <em>recommended</em> directive
144 violations) and <em>wishlist</em> (for <em>optional</em>
146 <p>Compare RFC 2119. Note, however, that these words are
147 used in a different way in this document.</p>
151 Much of the information presented in this manual will be
152 useful even when building a package which is to be
153 distributed in some other way or is intended for local use
159 <heading>New versions of this document</heading>
162 This manual is distributed via the Debian package
163 <package>debian-policy</package>.
167 The current version of this document is also available from
168 the Debian web mirrors at
169 <tt><url name="/doc/debian-policy/"
170 id="http://www.debian.org/doc/debian-policy/"></tt>
171 and from the Debian archive mirrors at
172 <tt><url name="/doc/package-developer/policy.txt.gz"
173 id="http://ftp.debian.org/debian/doc/package-developer/policy.txt.gz"></tt>.
174 Also available from the same directory are several other
175 formats: <file>policy.html.tar.gz</file>, <file>policy.pdf.gz</file>
176 and <file>policy.ps.gz</file>.
180 The <package>debian-policy</package> package also includes the file
181 <file>upgrading-checklist.txt</file> which indicates policy
182 changes between versions of this document.
187 <heading>Authors and Maintainers</heading>
190 Originally called "Debian GNU/Linux Policy Manual", this
191 manual was initially written in 1996 by Ian Jackson.
192 It was revised on November 27th, 1996 by David A. Morris.
193 Christian Schwarz added new sections on March 15th, 1997,
194 and reworked/restructured it in April-July 1997.
195 Christoph Lameter contributed the "Web Standard".
196 Julian Gilbey largely restructured it in 2001.
200 Since September 1998, the responsibility for the contents of
201 this document lies on the <url name="debian-policy mailing list"
202 id="mailto:debian-policy@lists.debian.org">. Proposals
203 are discussed there and inserted into policy after a certain
204 consensus is established.
205 <!-- insert shameless policy-process plug here eventually -->
206 The actual editing is done by a group of maintainers that have
207 no editorial powers. These are the current maintainers:
210 <item>Julian Gilbey</item>
211 <item>Branden Robinson</item>
212 <item>Josip Rodin</item>
213 <item>Manoj Srivastava</item>
218 While the authors of this document have tried hard to avoid
219 typos and other errors, these do still occur. If you discover
220 an error in this manual or if you want to give any
221 comments, suggestions, or criticisms please send an email to
222 the Debian Policy List,
223 <email>debian-policy@lists.debian.org</email>, or submit a
224 bug report against the <tt>debian-policy</tt> package.
228 Please do not try to reach the individual authors or maintainers
229 of the Policy Manual regarding changes to the Policy.
235 <heading>The Debian Archive</heading>
237 The Debian GNU/Linux system is maintained and distributed as a
238 collection of <em>packages</em>. Since there are so many of
239 them (currently well over 6000), they are split into
240 <em>sections</em> and given <em>priorities</em> to simplify
241 the handling of them.
244 The effort of the Debian project is to build a free operating
245 system, but not every package we want to make accessible is
246 <em>free</em> in our sense (see the Debian Free Software
247 Guidelines, below), or may be imported/exported without
248 restrictions. Thus, the archive is split into the sections
249 <em>main</em>, <em>non-free</em>, <em>contrib</em>,
250 <em>non-US/main</em>, <em>non-US/non-free</em>, and
251 <em>non-US/contrib</em>. The sections are explained in detail
256 The <em>main</em> and the <em>non-US/main</em> sections
257 together form the <em>Debian GNU/Linux distribution</em>.
261 Packages in the other sections are not considered to be part
262 of the Debian distribution, although we support their use and
263 provide infrastructure for them (such as our bug-tracking
264 system and mailing lists). This Debian Policy Manual applies
265 to these packages as well.</p>
267 <sect id="pkgcopyright">
268 <heading>Package copyright and sections</heading>
270 The aims of this section are:
272 <list compact="compact">
274 <p>to allow us to make as much software available as we
278 <p>to allow us to encourage everyone to write free
282 <p>to allow us to make it easy for people to produce
283 CD-ROMs of our system without violating any licenses,
284 import/export restrictions, or any other laws.</p>
289 <heading>The Debian Free Software Guidelines</heading>
291 The Debian Free Software Guidelines (DFSG) form our
292 definition of "free software". These are:
294 <tag>Free Redistribution
298 The license of a Debian component may not restrict any
299 party from selling or giving away the software as a
300 component of an aggregate software distribution
301 containing programs from several different
302 sources. The license may not require a royalty or
303 other fee for such sale.
310 The program must include source code, and must allow
311 distribution in source code as well as compiled form.
318 The license must allow modifications and derived
319 works, and must allow them to be distributed under the
320 same terms as the license of the original software.
323 <tag>Integrity of The Author's Source Code
327 The license may restrict source-code from being
328 distributed in modified form <em>only</em> if the
329 license allows the distribution of "patch files"
330 with the source code for the purpose of modifying the
331 program at build time. The license must explicitly
332 permit distribution of software built from modified
333 source code. The license may require derived works to
334 carry a different name or version number from the
335 original software. (This is a compromise. The Debian
336 Project encourages all authors to not restrict any
337 files, source or binary, from being modified.)
340 <tag>No Discrimination Against Persons or Groups
344 The license must not discriminate against any person
348 <tag>No Discrimination Against Fields of Endeavor
352 The license must not restrict anyone from making use
353 of the program in a specific field of endeavor. For
354 example, it may not restrict the program from being
355 used in a business, or from being used for genetic
359 <tag>Distribution of License
363 The rights attached to the program must apply to all
364 to whom the program is redistributed without the need
365 for execution of an additional license by those
369 <tag>License Must Not Be Specific to Debian
373 The rights attached to the program must not depend on
374 the program's being part of a Debian system. If the
375 program is extracted from Debian and used or
376 distributed without Debian but otherwise within the
377 terms of the program's license, all parties to whom
378 the program is redistributed must have the same
379 rights as those that are granted in conjunction with
383 <tag>License Must Not Contaminate Other Software
387 The license must not place restrictions on other
388 software that is distributed along with the licensed
389 software. For example, the license must not insist
390 that all other programs distributed on the same medium
391 must be free software.
394 <tag>Example Licenses
398 The "GPL," "BSD," and "Artistic" licenses are examples of
399 licenses that we consider <em>free</em>.
406 <heading>The main section</heading>
408 Every package in <em>main</em> and <em>non-US/main</em>
409 must comply with the DFSG (Debian Free Software
413 In addition, the packages in <em>main</em>
414 <list compact="compact">
417 must not require a package outside of <em>main</em>
418 for compilation or execution (thus, the package must
419 not declare a "Depends", "Recommends", or
420 "Build-Depends" relationship on a non-<em>main</em>
426 must not be so buggy that we refuse to support them,
432 must meet all policy requirements presented in this
439 Similarly, the packages in <em>non-US/main</em>
440 <list compact="compact">
443 must not require a package outside of <em>main</em>
444 or <em>non-US/main</em> for compilation or
450 must not be so buggy that we refuse to support them,
455 must meet all policy requirements presented in this
463 <heading>The contrib section</heading>
465 Every package in <em>contrib</em> and
466 <em>non-US/contrib</em> must comply with the DFSG.
470 In addition, the packages in <em>contrib</em> and
471 <em>non-US/contrib</em>
472 <list compact="compact">
475 must not be so buggy that we refuse to support them,
481 must meet all policy requirements presented in this
489 Furthermore, packages in <em>contrib</em> must not require
490 a package in a <em>non-US</em> section for compilation or
495 Examples of packages which would be included in
496 <em>contrib</em> or <em>non-US/contrib</em> are:
497 <list compact="compact">
500 free packages which require <em>contrib</em>,
501 <em>non-free</em> packages or packages which are not
502 in our archive at all for compilation or execution,
508 wrapper packages or other sorts of free accessories for
516 <heading>The non-free section</heading>
518 Packages must be placed in <em>non-free</em> or
519 <em>non-US/non-free</em> if they are not compliant with
520 the DFSG or are encumbered by patents or other legal
521 issues that make their distribution problematic.
524 In addition, the packages in <em>non-free</em> and
525 <em>non-US/non-free</em>
526 <list compact="compact">
529 must not be so buggy that we refuse to support them,
535 must meet all policy requirements presented in this
536 manual that it is possible for them to meet.<footnote>
538 It is possible that there are policy
539 requirements which the package is unable to
540 meet, for example, if the source is
541 unavailable. These situations will need to be
542 handled on a case-by-case basis.
552 <heading>The non-US sections</heading>
554 Non-free programs with cryptographic program code need to
555 be stored on the <em>non-us</em> server because of export
556 restrictions of the U.S.
559 Programs which use patented algorithms that have a
560 restrictied license also need to be stored on "non-us",
561 since that is located in a country where it is not allowed
562 to patent algorithms.
565 A package depends on another package which is distributed
566 via the non-us server has to be stored on the non-us
571 <heading>Further copyright considerations</heading>
573 Every package must be accompanied by a verbatim copy of
574 its copyright and distribution license in the file
575 <file>/usr/share/doc/<var>package</var>/copyright</file>
576 (see <ref id="copyrightfile"> for further details).
579 We reserve the right to restrict files from being included
580 anywhere in our archives if
581 <list compact="compact">
584 their use or distribution would break a law,
589 there is an ethical conflict in their distribution or
595 we would have to sign a license for them, or
600 their distribution would conflict with other project
608 Programs whose authors encourage the user to make
609 donations are fine for the main distribution, provided
610 that the authors do not claim that not donating is
611 immoral, unethical, illegal or something similar; in such
612 a case they must go in <em>non-free</em>.</p>
615 Packages whose copyright permission notices (or patent
616 problems) do not even allow redistribution of binaries
617 only, and where no special permission has been obtained,
618 must not be placed on the Debian FTP site and its mirrors
622 Note that under international copyright law (this applies
623 in the United States, too), <em>no</em> distribution or
624 modification of a work is allowed without an explicit
625 notice saying so. Therefore a program without a copyright
626 notice <em>is</em> copyrighted and you may not do anything
627 to it without risking being sued! Likewise if a program
628 has a copyright notice but no statement saying what is
629 permitted then nothing is permitted.</p>
632 Many authors are unaware of the problems that restrictive
633 copyrights (or lack of copyright notices) can cause for
634 the users of their supposedly-free software. It is often
635 worthwhile contacting such authors diplomatically to ask
636 them to modify their license terms. However, this can be a
637 politically difficult thing to do and you should ask for
638 advice on the <tt>debian-legal</tt> mailing list first, as
643 When in doubt about a copyright, send mail to
644 <email>debian-legal@lists.debian.org</email>. Be prepared
645 to provide us with the copyright statement. Software
646 covered by the GPL, public domain software and BSD-like
647 copyrights are safe; be wary of the phrases "commercial
648 use prohibited" and "distribution restricted".
652 <heading>Subsections</heading>
655 The packages in the sections <em>main</em>,
656 <em>contrib</em> and <em>non-free</em> are grouped further
657 into <em>subsections</em> to simplify handling.
661 The section and subsection for each package should be
662 specified in the package's <tt>Section</tt> control
663 record. However, the maintainer of the Debian archive
664 may override this selection to ensure the consistency of
665 the Debian distribution. The <tt>Section</tt> field
666 should be of the form:
667 <list compact="compact">
670 <em>subsection</em> if the package is in the
671 <em>main</em> section,
676 <em>section/subsection</em> if the package is in
677 the <em>contrib</em> or <em>non-free</em> section,
683 <tt>non-US</tt>, <tt>non-US/contrib</tt> or
684 <tt>non-US/non-free</tt> if the package is in
685 <em>non-US/main</em>, <em>non-US/contrib</em> or
686 <em>non-US/non-free</em> respectively.
693 The Debian archive maintainers provide the authoritative
694 list of subsections. At present, they are:
695 <em>admin</em>, <em>base</em>, <em>comm</em>,
696 <em>contrib</em>, <em>devel</em>, <em>doc</em>,
697 <em>editors</em>, <em>electronics</em>, <em>games</em>,
698 <em>graphics</em>, <em>hamradio</em>,
699 <em>interpreters</em>, <em>libs</em>, <em>mail</em>,
700 <em>math</em>, <em>misc</em>, <em>net</em>, <em>news</em>,
701 <em>non-US</em>, <em>non-free</em>, <em>oldlibs</em>,
702 <em>otherosfs</em>, <em>science</em>, <em>shells</em>,
703 <em>sound</em>, <em>tex</em>, <em>text</em>,
704 <em>utils</em>, <em>web</em>, <em>x11</em>.
708 <heading>Priorities</heading>
711 Each package should have a <em>priority</em> value, which is
712 included in the package's <em>control record</em>. This
713 information is used by the Debian package management tools
714 to separate high-priority packages from less-important
718 The following <em>priority levels</em> are recognised by the
719 Debian package management tools.
721 <tag><tt>required</tt></tag>
724 Packages which are necessary for the proper
725 functioning of the system. You must not remove these
726 packages or your system may become totally broken and
727 you may not even be able to use <prgn>dpkg</prgn> to
728 put things back. Systems with only the
729 <tt>required</tt> packages are probably unusable, but
730 they do have enough functionality to allow the
731 sysadmin to boot and install more software.</p>
733 <tag><tt>important</tt></tag>
736 Important programs, including those which one would
737 expect to find on any Unix-like system. If the
738 expectation is that an experienced Unix person who
739 found it missing would say "What on earth is going on,
740 where is <prgn>foo</prgn>?", it must be an
741 <tt>important</tt> package.<footnote>
743 This is an important criterion because we are
744 trying to produce, amongst other things, a free
748 Other packages without which the system will not run
749 well or be usable must also have priority
750 <tt>important</tt>. This does
751 <em>not</em> include Emacs, the X Window System, TeX
752 or any other large applications. The
753 <tt>important</tt> packages are just a bare minimum of
754 commonly-expected and necessary tools.</p>
756 <tag><tt>standard</tt></tag>
759 These packages provide a reasonably small but not too
760 limited character-mode system. This is what will be
761 installed by default if the user doesn't select anything
762 else. It doesn't include many large applications.</p>
764 <tag><tt>optional</tt></tag>
767 (In a sense everything that isn't required is
768 optional, but that's not what is meant here.) This is
769 all the software that you might reasonably want to
770 install if you didn't know what it was and don't have
771 specialized requirements. This is a much larger system
772 and includes the X Window System, a full TeX
773 distribution, and many applications. Note that
774 optional packages should not conflict with each other.
777 <tag><tt>extra</tt></tag>
780 This contains all packages that conflict with others
781 with required, important, standard or optional
782 priorities, or are only likely to be useful if you
783 already know what they are or have specialised
790 Packages must not depend on packages with lower priority
791 values (excluding build-time dependencies). In order to
792 ensure this, the priorities of one or more packages may need
798 <heading>Binary packages</heading>
801 The Debian GNU/Linux distribution is based on the Debian
802 package management system, called <prgn>dpkg</prgn>. Thus,
803 all packages in the Debian distribution must be provided
804 in the <tt>.deb</tt> file format.</p>
808 <heading>The package name</heading>
811 Every package must have a name that's unique within the Debian
815 Package names must consist only of lower case letters
816 (<tt>a-z</tt>), digits (<tt>0-9</tt>), plus (<tt>+</tt>)
817 and minus (<tt>-</tt>) signs, and periods (<tt>.</tt>).
818 They must be at least two characters long and must start
819 with an alphanumeric character.
823 The package name is part of the file name of the
824 <tt>.deb</tt> file and is included in the control field
830 <heading>The maintainer of a package</heading>
832 Every package must have a Debian maintainer (the
833 maintainer may be one person or a group of people
834 reachable from a common email address, such as a mailing
835 list). The maintainer is responsible for ensuring that
836 the package is placed in the appropriate distributions.
840 The maintainer must be specified in the
841 <tt>Maintainer</tt> control field with their correct name
842 and a working email address. If one person maintains
843 several packages, he/she should try to avoid having
844 different forms of their name and email address in
845 the <tt>Maintainer</tt> fields of those packages.
849 If the maintainer of a package quits from the Debian
850 project, "Debian QA Group"
851 <email>packages@qa.debian.org</email> takes over the
852 maintainership of the package until someone else
853 volunteers for that task. These packages are called
854 <em>orphaned packages</em>.<footnote>
856 The detailed procedure for doing this gracefully can
857 be found in the Debian Developer's Reference, either
858 in the <tt>developers-reference</tt> package, or on
859 the Debian FTP server
860 <ftpsite>ftp.debian.org</ftpsite> as
861 <ftppath>/debian/doc/package-developer/developers-reference.txt.gz</ftppath>
863 id="http://www.debian.org/doc/packaging-manuals/developers-reference/"
864 name="Debian Developer's Reference"> webpage.
872 <heading>The description of a package</heading>
875 Every Debian package must have an extended description
876 stored in the appropriate field of the control record.</p>
879 The description should be written so that it gives the
880 system administrator enough information to decide whether
881 to install the package. This description should not just
882 be copied verbatim from the program's documentation.
883 Instructions for configuring or using the package should
884 not be included (that is what installation scripts,
885 manual pages, info files, etc., are for). Copyright
886 statements and other administrivia should not be included
887 either (that is what the copyright file is for).
891 Please refer to <ref id="descriptions"> for more information.
898 <heading>Dependencies</heading>
901 Every package must specify the dependency information
902 about other packages that are required for the first to
906 For example, a dependency entry must be provided for any
907 shared libraries required by a dynamically-linked executable
908 binary in a package.</p>
911 Packages are not required to declare any dependencies they
912 have on other packages which are marked <tt>Essential</tt>
913 (see below), and should not do so unless they depend on a
914 particular version of that package.</p>
917 Sometimes, a package requires another package to be installed
918 <em>and</em> configured before it can be installed. In this
919 case, you must specify a <tt>Pre-Depends</tt> entry for
923 You should not specify a <tt>Pre-Depends</tt> entry for a
924 package before this has been discussed on the
925 <tt>debian-devel</tt> mailing list and a consensus about
926 doing that has been reached.</p></sect1>
929 <sect1 id="virtual_pkg">
930 <heading>Virtual packages</heading>
933 Sometimes, there are several packages which offer
934 more-or-less the same functionality. In this case, it's
935 useful to define a <em>virtual package</em> whose name
936 describes that common functionality. (The virtual
937 packages only exist logically, not physically; that's why
938 they are called <em>virtual</em>.) The packages with this
939 particular function will then <em>provide</em> the virtual
940 package. Thus, any other package requiring that function
941 can simply depend on the virtual package without having to
942 specify all possible packages individually.</p>
945 All packages should use virtual package names where
946 appropriate, and arrange to create new ones if necessary.
947 They should not use virtual package names (except privately,
948 amongst a cooperating group of packages) unless they have
949 been agreed upon and appear in the list of virtual package
950 names. (See also <ref id="virtual">)</p>
953 The latest version of the authoritative list of virtual
954 package names can be found in the <tt>debian-policy</tt> package.
955 It's also available from the Debian web mirrors at
956 <tt><url name="/doc/packaging-manuals/virtual-package-names-list.txt"
957 id="http://www.debian.org/doc/packaging-manuals/virtual-package-names-list.txt"></tt>
958 and from the Debian archive mirrors at
959 <tt><url name="/doc/package-developer/virtual-package-names-list.txt"
960 id="http://ftp.debian.org/debian/doc/package-developer/virtual-package-names-list.txt"></tt>.
964 The procedure for updating the list is described in the preface
971 <heading>Base system</heading>
974 The <tt>base system</tt> is a minimum subset of the Debian
975 GNU/Linux system that is installed before everything else
976 on a new system. Thus, only very few packages are allowed
977 to go into the <tt>base</tt> section to keep the required
978 disk usage very small.</p>
981 Most of these packages will have the priority value
982 <tt>required</tt> or at least <tt>important</tt>, and many
983 of them will be tagged <tt>essential</tt> (see below).</p>
990 <heading>Essential packages</heading>
993 Some packages are tagged <tt>essential</tt>. (They have
994 <tt>Essential: yes</tt> in their package control record.)
995 This flag is used for packages that are <em>essential</em>
999 Since these packages cannot be easily removed (one has to
1000 specify an extra <em>force option</em> to
1001 <prgn>dpkg</prgn> to do so), this flag must not be used
1002 unless absolutely necessary. A shared library package
1003 must not be tagged <tt>essential</tt>; dependencies will
1004 prevent its premature removal, and we need to be able to
1005 remove it when it has been superseded.
1009 Since dpkg will not prevent upgrading of other packages
1010 while an <tt>essential</tt> package is in an unconfigured
1011 state, all <tt>essential</tt> packages must supply all of
1012 their core functionality even when unconfigured. If the
1013 package cannot satisfy this requirement it must not be
1014 tagged as essential, and any packages depending on this
1015 package must instead have explicit dependency fields as
1020 You must not tag any packages <tt>essential</tt> before
1021 this has been discussed on the <tt>debian-devel</tt>
1022 mailing list and a consensus about doing that has been
1027 <heading>Tasks</heading>
1030 The Debian install process allows the user to choose from
1031 a number of common tasks which a Debian system can be used to
1032 perform. Selecting a task with <prgn>tasksel</prgn> causes
1033 a set of packages that are useful in performing that task to be
1038 This set of packages is all available packages which have the
1039 name of the selected task in the <tt>Task</tt> field of their
1040 control file. The format of this field is a list of tasks,
1041 separated by commas.
1045 You should not tag any packages as belonging to a task
1046 before this has been discussed on the
1047 <em>debian-devel</em> mailing list and a consensus about
1048 doing that has been reached.
1052 For third parties (and historical reasons), tasksel also
1053 supports constructing tasks based on <em>task
1054 packages</em>. These are packages whose names begin with
1055 <em>task-</em>. Task packages should not be included in the
1060 <sect1 id="maintscripts">
1061 <heading>Maintainer Scripts</heading>
1064 The package installation scripts should avoid producing
1065 output which it is unnecessary for the user to see and
1066 should rely on <prgn>dpkg</prgn> to stave off boredom on
1067 the part of a user installing many packages. This means,
1068 amongst other things, using the <tt>--quiet</tt> option on
1069 <prgn>install-info</prgn>.</p>
1072 Errors which occur during the execution of an installation
1073 script must be checked and the installation must not
1074 continue after an error.
1078 Note that in general <ref id="scripts"> applies to package
1079 maintainer scripts, too.
1083 You should not use <prgn>dpkg-divert</prgn> on a file
1084 belonging to another package without consulting the
1085 maintainer of that package first.
1089 All packages which supply an instance of a common command
1090 name (or, in general, filename) should generally use
1091 <prgn>update-alternatives</prgn>, so that they may be
1092 installed together. If <prgn>update-alternatives</prgn>
1093 is not used, then each package must use
1094 <tt>Conflicts</tt> to ensure that other packages are
1095 de-installed. (In this case, it may be appropriate to
1096 specify a conflict against earlier versions of something
1097 that previously did not use
1098 <prgn>update-alternatives</prgn>; this is an exception to
1099 the usual rule that versioned conflicts should be
1105 <heading>Prompting in maintainer scripts</heading>
1107 Package maintainer scripts may prompt the user if
1108 necessary. Prompting may be accomplished by
1110 <p>From the Jasrgon file: by hand 2. By extension,
1111 writing code which does something in an explicit or
1112 low-level way for which a presupplied library
1113 (<em>debconf, in this instance</em>) routine ought
1114 to have been available.</p>
1115 </footnote> (but this is deprecated), or by
1116 communicating though a program, which conforms to the
1117 Debian Configuration management specification, version 2
1118 or higher (such as <prgn>debconf</prgn>). Thiss
1119 specification is included in the
1120 <file>debconf_specification</file> files in the
1121 <package>debian-policy</package> package. You may also
1122 find this file on the FTP site
1123 <ftpsite>ftp.debian.org</ftpsite> in
1124 <ftppath>/debian/doc/package-developer/debconf_specification.txt.gz</ftppath>
1125 or on your local mirror.<footnote>
1127 6% of Debian packages [see <url
1128 id="http://auric.debian.org/%7Ejoeyh/debconf-stats/data/"
1129 name="Debconf stats">] currently use
1130 <package>debconf</package> to prompt the user at
1131 install time, and this number is growing daily. The
1132 benefits of using debconf are briefly explained at
1134 id="http://kitenet.net/doc/debconf-doc/introduction.html"
1135 name="Debconf introduction">; they include
1136 preconfiguration, (mostly) noninteractive
1137 installation, elimination of redundant prompting,
1138 consistency of user interface, etc.
1141 With this increasing number of packages using
1142 <package>debconf</package>, plus the existance of a
1143 nascent second implementation of the Debian
1144 configuration management system
1145 (<package>cdebconf</package>), and the stabilization
1146 of the protocol these things use, the time has
1147 finally come to reflect the use of these things in
1154 Packages which use the Debian Configuration management
1155 specification may contain an additional
1156 <prgn>config</prgn> script and a <tt>templates</tt>
1157 file in their control archive. The <prgn>config</prgn>
1158 script might be run before the <prgn>preinst</prgn>
1159 script, and before the package is unpacked or any of its
1160 dependencies or pre-dependancies are satisfied.
1161 Therefore it must work using only the tools present in
1162 <em>essential</em> packages.<footnote>
1164 <package>Debconf</package> or another tool that
1165 implements the Debian Configuration management
1166 specification will also be installed, and any
1167 versioned dependencies on it will be satisfied
1168 before preconfiguration begins.
1174 Packages should try to minimize the amount of prompting
1175 they need to do, and they should ensure that the user
1176 will only ever be asked each question once. This means
1177 that packages should try to use appropriate shared
1178 configuration files (such as <file>/etc/papersize</file> and
1179 <file>/etc/news/server</file>), and shared
1180 <package>debconf</package> variables rather than each
1181 prompting for their own list of required pieces of
1186 It also means that an upgrade should not ask the same
1187 questions again, unless the user has used <tt>dpkg
1188 --purge</tt> to remove the package's configuration. The
1189 answers to configuration questions should be stored in an
1190 appropriate place in <file>/etc</file> so that the user can
1191 modify them, and how this has been done should be
1195 If a package has a vitally important piece of
1196 information to pass to the user (such as "don't run me
1197 as I am, you must edit the following configuration files
1198 first or you risk your system emitting badly-formatted
1199 messages"), it should display this in the
1200 <prgn>config</prgn> or <prgn>postinst</prgn> script and
1201 prompt the user to hit return to acknowledge the
1202 message. Copyright messages do not count as vitally
1203 important (they belong in
1204 <file>/usr/share/doc/<var>package</var>/copyright</file>);
1205 neither do instructions on how to use a program (these
1206 should be in on-line documentation, where all the users
1210 Any necessary prompting should almost always be confined
1211 to the <prgn>config</prgn> or <prgn>postinst</prgn>
1212 script. If it is done in the <prgn>postinst</prgn>, it
1213 should be protected with a conditional so that
1214 unnecessary prompting doesn't happen if a package's
1215 installation fails and the <prgn>postinst</prgn> is
1216 called with <tt>abort-upgrade</tt>,
1217 <tt>abort-remove</tt> or <tt>abort-deconfigure</tt>.</p>
1222 <heading>Source packages</heading>
1224 <sect1 id="standardsversion">
1225 <heading>Standards conformance</heading>
1228 In the source package's <tt>Standards-Version</tt> control
1229 field, you should specify the most recent version number
1230 of this policy document with which your package complied
1231 when it was last updated. The current version number is
1236 This information may be used to file bug reports
1237 automatically if your package becomes too much out of
1242 The version number has four components: major and minor
1243 version number and major and minor patch level. When the
1244 standards change in a way that requires every package to
1245 change the major number will be changed. Significant
1246 changes that will require work in many packages will be
1247 signaled by a change to the minor number. The major patch
1248 level will be changed for any change to the meaning of the
1249 standards, however small; the minor patch level will be
1250 changed when only cosmetic, typographical or other edits
1251 are made which neither change the meaning of the document
1252 nor affect the contents of packages.</p>
1255 Thus only the first three components of the policy version
1256 are significant in the <em>Standards-Version</em> control
1257 field, and so either these three components or the all
1258 four components may be specified.<footnote>
1260 In the past, people specified the full version number
1261 in the Standards-Version field, for example "2.3.0.0".
1262 Since minor patch-level changes don't introduce new
1263 policy, it was thought it would be better to relax
1264 policy and only require the first 3 components to be
1265 specified, in this example "2.3.0". All four
1266 components may still be used if someone wishes to do
1273 You should regularly, and especially if your package has
1274 become out of date, check for the newest Policy Manual
1275 available and update your package, if necessary. When your
1276 package complies with the new standards you should update the
1277 <tt>Standards-Version</tt> source package field and
1278 release it.<footnote>
1280 See the file <file>upgrading-checklist</file> for
1281 information about policy which has changed between
1282 different versions of this document.
1289 <sect1 id="pkg-relations">
1290 <heading>Package relationships</heading>
1293 Source packages should specify which binary packages they
1294 require to be installed or not to be installed in order to
1295 build correctly. For example, if building a package
1296 requires a certain compiler, then the compiler should be
1297 specified as a build-time dependency.
1301 It is not necessary to explicitly specify build-time
1302 relationships on a minimal set of packages that are always
1303 needed to compile, link and put in a Debian package a
1304 standard "Hello World!" program written in C or C++. The
1305 required packages are called <em>build-essential</em>, and
1306 an informational list can be found in
1307 <file>/usr/share/doc/build-essential/list</file> (which is
1308 contained in the <tt>build-essential</tt>
1311 <list compact="compact">
1313 <p>This allows maintaining the list separately
1314 from the policy documents (the list does not
1315 need the kind of control that the policy
1321 Having a separate package allows one to install
1322 the build-essential packages on a machine, as
1323 well as allowing other packages such as tasks to
1324 require installation of the build-essential
1325 packages using the depends relation.
1330 The separate package allows bug reports against
1331 the list to be categorized separately from
1332 the policy management process in the BTS.
1342 When specifying the set of build-time dependencies, one
1343 should list only those packages explicitly required by the
1344 build. It is not necessary to list packages which are
1345 required merely because some other package in the list of
1346 build-time dependencies depends on them.<footnote>
1348 The reason for this is that dependencies change, and
1349 you should list all those packages, and <em>only</em>
1350 those packages that <em>you</em> need directly. What
1351 others need is their business. For example, if you
1352 only link against <file>libimlib</file>, you will need to
1353 build-depend on <package>libimlib2-dev</package> but
1354 not against any <tt>libjpeg*</tt> packages, even
1355 though <tt>libimlib2-dev</tt> currently depends on
1356 them: installation of <package>libimlib2-dev</package>
1357 will automatically ensure that all of its run-time
1358 dependencies are satisfied.
1364 If build-time dependencies are specified, it must be
1365 possible to build the package and produce working binaries
1366 on a system with only essential and build-essential
1367 packages installed and also those required to satisfy the
1368 build-time relationships (including any implied
1369 relationships). In particular, this means that version
1370 clauses should be used rigorously in build-time
1371 relationships so that one cannot produce bad or
1372 inconsistently configured packages when the relationships
1373 are properly satisfied.
1377 <ref id="relationships"> explains the technical details.
1381 <heading>Changes to the upstream sources</heading>
1384 If changes to the source code are made that are not
1385 specific to the needs of the Debian system, they should be
1386 sent to the upstream authors in whatever form they prefer
1387 so as to be included in the upstream version of the
1391 If you need to configure the package differently for
1392 Debian or for Linux, and the upstream source doesn't
1393 provide a way to do so, you should add such configuration
1394 facilities (for example, a new <prgn>autoconf</prgn> test
1395 or <tt>#define</tt>) and send the patch to the upstream
1396 authors, with the default set to the way they originally
1397 had it. You can then easily override the default in your
1398 <file>debian/rules</file> or wherever is appropriate.</p>
1401 You should make sure that the <prgn>configure</prgn> utility
1402 detects the correct architecture specification string
1403 (refer to <ref id="arch-spec"> for details).</p>
1406 If you need to edit a <prgn>Makefile</prgn> where
1407 GNU-style <prgn>configure</prgn> scripts are used, you
1408 should edit the <file>.in</file> files rather than editing the
1409 <prgn>Makefile</prgn> directly. This allows the user to
1410 reconfigure the package if necessary. You should
1411 <em>not</em> configure the package and edit the generated
1412 <prgn>Makefile</prgn>! This makes it impossible for
1413 someone else to later reconfigure the package.</p>
1416 You should document your changes and updates to the source
1417 package properly in the <file>debian/changelog</file> file.
1418 For more information, please see <ref id="changelogs">.
1424 <heading>Error trapping in makefiles</heading>
1427 When <prgn>make</prgn> invokes a command in a makefile
1428 (including your package's upstream makefiles and
1429 <file>debian/rules</file>), it does so using <prgn>sh</prgn>. This
1430 means that <prgn>sh</prgn>'s usual bad error handling
1431 properties apply: if you include a miniature script as one
1432 of the commands in your makefile you'll find that if you
1433 don't do anything about it then errors are not detected
1434 and <prgn>make</prgn> will blithely continue after
1438 Every time you put more than one shell command (this
1439 includes using a loop) in a makefile command you
1440 must make sure that errors are trapped. For
1441 simple compound commands, such as changing directory and
1442 then running a program, using <tt>&&</tt> rather
1443 than semicolon as a command separator is sufficient. For
1444 more complex commands including most loops and
1445 conditionals you should include a separate <tt>set -e</tt>
1446 command at the start of every makefile command that's
1447 actually one of these miniature shell scripts.</p></sect1>
1451 <heading>Obsolete constructs and libraries</heading>
1454 The include file <tt><varargs.h></tt> is
1455 provided to support end-users compiling very old software;
1456 the library <tt>libtermcap</tt> is provided to support the
1457 execution of software which has been linked against it
1458 (either old programs or those such as Netscape which are
1459 only available in binary form).</p>
1462 Debian packages should be patched to use
1463 <tt><stdarg.h></tt> and <tt>ncurses</tt>
1470 <chapt id="controlfields"><heading>Control files and their fields</heading>
1473 Many of the tools in the package management suite manipulate
1474 data represented in a common format, known as <em>control
1475 data</em>. The data is often stored in <em>control
1476 files</em>. Binary and source packages have control files,
1477 and the <file>.changes</file> files which control the installation
1478 of uploaded files are also in control file format.
1479 <prgn>dpkg</prgn>'s internal databases are in a similar
1483 <sect id="controlsyntax"><heading>Syntax of control files</heading>
1486 A control file consists of one or more paragraphs of fields.
1487 The paragraphs are separated by blank lines. Some control
1488 files allow only one paragraph; others allow several, in
1489 which case each paragraph usually refers to a different
1490 package. (For example, in source packages, the first
1491 paragraph refers to the source package, and later paragraphs
1492 refer to binary packages generated from the source.)
1496 Each paragraph consists of a series of data fields; each
1497 field consists of the field name, followed by a colon and
1498 then the data/value associated with that field. It ends at
1499 the end of the line. Horizontal whitespace (spaces and
1500 tabs) may occur immediately before or after the value and is
1501 ignored there; it is conventional to put a single space
1502 after the colon. For example, a field might be:
1503 <example compact="compact">
1506 the field name is <tt>Package</tt> and the field value
1511 Some fields' values may span several lines; in this case
1512 each continuation line <em>must</em> start with a space or
1513 tab. Any trailing spaces or tabs at the end of individual
1514 lines of a field value are ignored.
1518 Except where otherwise stated only a single line of data is
1519 allowed and whitespace is not significant in a field body.
1520 Whitespace must not appear inside names (of packages,
1521 architectures, files or anything else) or version numbers,
1522 or between the characters of multi-character version
1527 Field names are not case-sensitive, but it is usual to
1528 capitalize the field names using mixed case as shown below.
1532 Blank lines, or lines consisting only of spaces and tabs,
1533 are not allowed within field values or between fields - that
1534 would mean a new paragraph.
1539 <sect><heading>List of fields</heading>
1541 This list here is not supposed to be exhaustive. Most fields
1542 are dealt with elsewhere in this document.
1544 <sect1 id="f-Package"><heading><tt>Package</tt>
1548 The name of the binary package. Package names consist of
1549 lower case letters (<tt>a-z</tt>), digits (<tt>0-9</tt>),
1550 plus (<tt>+</tt>) and minus (<tt>-</tt>) signs, and
1551 periods (<tt>.</tt>).
1555 They must be at least two characters long and must start
1556 with an alphanumeric character. The use of lowercase
1557 package names is required unless the package you're
1558 building (or referring to, in other fields) is already
1559 using uppercase characters.</p>
1562 <sect1 id="f-Version"><heading><tt>Version</tt>
1566 This lists the source or binary package's version number -
1567 see <ref id="versions">.
1573 id="f-Standards-Version"><heading><tt>Standards-Version</tt>
1577 The most recent version of the standards (the policy
1578 manual and associated texts) with which the package
1579 complies. This is updated manually when editing the
1580 source package to conform to newer standards; it can
1581 sometimes be used to tell when a package needs attention.
1582 Its format is described above; see
1583 <ref id="standardsversion">.
1588 <sect1 id="f-Distribution"><heading><tt>Distribution</tt>
1592 In a <file>.changes</file> file or parsed changelog output
1593 this contains the (space-separated) name(s) of the
1594 distribution(s) where this version of the package should
1595 be installed. Valid distributions are determined by the
1596 archive maintainers.<footnote>
1597 Current distribution names are:
1598 <taglist compact="compact">
1599 <tag><em>stable</em></tag>
1602 This is the current "released" version of Debian
1603 GNU/Linux. Once the distribution is
1604 <em>stable</em> only security fixes and other
1605 major bug fixes are allowed. When changes are
1606 made to this distribution, the release number is
1607 increased (for example: 2.2r1 becomes 2.2r2 then
1612 <tag><em>unstable</em></tag>
1615 This distribution value refers to the
1616 <em>developmental</em> part of the Debian
1617 distribution tree. New packages, new upstream
1618 versions of packages and bug fixes go into the
1619 <em>unstable</em> directory tree. Download from
1620 this distribution at your own risk.
1624 <tag><em>testing</em></tag>
1627 This distribution value refers to the
1628 <em>testing</em> part of the Debian distribution
1629 tree. It receives its packages from the
1630 unstable distribution after a short time lag to
1631 ensure that there are no major issues with the
1632 unstable packages. It is less prone to breakage
1633 than unstable, but still risky. It is not
1634 possible to upload packages directly to
1639 <tag><em>frozen</em></tag>
1642 From time to time, the <em>testing</em>
1643 distribution enters a state of "code-freeze" in
1644 anticipation of release as a <em>stable</em>
1645 version. During this period of testing only
1646 fixes for existing or newly-discovered bugs will
1647 be allowed. The exact details of this stage are
1648 determined by the Release Manager.
1652 <tag><em>experimental</em></tag>
1655 The packages with this distribution value are
1656 deemed by their maintainers to be high
1657 risk. Oftentimes they represent early beta or
1658 developmental packages from various sources that
1659 the maintainers want people to try, but are not
1660 ready to be a part of the other parts of the
1661 Debian distribution tree. Download at your own
1667 You should list <em>all</em> distributions that the
1668 package should be installed into.
1677 <chapt id="versions"><heading>Version numbering</heading>
1680 Every package has a version number recorded in its
1681 <tt>Version</tt> control file field.
1685 The package management system imposes an ordering on version
1686 numbers, so that it can tell whether packages are being up- or
1687 downgraded and so that package system front end applications
1688 can tell whether a package it finds available is newer than
1689 the one installed on the system. The version number format
1690 has the most significant parts (as far as comparison is
1691 concerned) at the beginning.
1695 The version number format is:
1696 [<var>epoch</var><tt>:</tt>]<var>upstream_version</var>[<tt>-</tt><var>debian_revision</var>]
1700 The three components here are:
1702 <tag><var>epoch</var></tag>
1705 This is a single (generally small) unsigned integer. It
1706 may be omitted, in which case zero is assumed. If it is
1707 omitted then the <var>upstream_version</var> may not
1712 It is provided to allow mistakes in the version numbers
1713 of older versions of a package, and also a package's
1714 previous version numbering schemes, to be left behind.
1718 <tag><var>upstream_version</var></tag>
1721 This is the main part of the version number. It is
1722 usually the version number of the original ("upstream")
1723 package from which the <file>.deb</file> file has been made,
1724 if this is applicable. Usually this will be in the same
1725 format as that specified by the upstream author(s);
1726 however, it may need to be reformatted to fit into the
1727 package management system's format and comparison
1732 The comparison behavior of the package management system
1733 with respect to the <var>upstream_version</var> is
1734 described below. The <var>upstream_version</var>
1735 portion of the version number is mandatory.
1739 The <var>upstream_version</var> may contain only
1740 alphanumerics<footnote>
1741 <p>Alphanumerics are <tt>A-Za-z0-9</tt> only.</p>
1743 and the characters <tt>.</tt> <tt>+</tt> <tt>-</tt>
1744 <tt>:</tt> (full stop, plus, hyphen, colon) and should
1745 start with a digit. If there is no
1746 <var>debian_revision</var> then hyphens are not allowed;
1747 if there is no <var>epoch</var> then colons are not
1751 <tag><var>debian_revision</var></tag>
1754 This part of the version number specifies the version of
1755 the Debian package based on the upstream version. It
1756 may contain only alphanumerics and the characters
1757 <tt>+</tt> and <tt>.</tt> (plus and full stop) and is
1758 compared in the same way as the
1759 <var>upstream_version</var> is.
1763 It is optional; if it isn't present then the
1764 <var>upstream_version</var> may not contain a hyphen.
1765 This format represents the case where a piece of
1766 software was written specifically to be turned into a
1767 Debian package, and so there is only one "debianization"
1768 of it and therefore no revision indication is required.
1772 It is conventional to restart the
1773 <var>debian_revision</var> at <tt>1</tt> each time the
1774 <var>upstream_version</var> is increased.
1778 The package management system will break the version
1779 number apart at the last hyphen in the string (if there
1780 is one) to determine the <var>upstream_version</var> and
1781 <var>debian_revision</var>. The absence of a
1782 <var>debian_revision</var> compares earlier than the
1783 presence of one (but note that the
1784 <var>debian_revision</var> is the least significant part
1785 of the version number).
1792 The <var>upstream_version</var> and <var>debian_revision</var>
1793 parts are compared by the package management system using the
1798 The strings are compared from left to right.
1802 First the initial part of each string consisting entirely of
1803 non-digit characters is determined. These two parts (one of
1804 which may be empty) are compared lexically. If a difference
1805 is found it is returned. The lexical comparison is a
1806 comparison of ASCII values modified so that all the letters
1807 sort earlier than all the non-letters.
1811 Then the initial part of the remainder of each string which
1812 consists entirely of digit characters is determined. The
1813 numerical values of these two parts are compared, and any
1814 difference found is returned as the result of the comparison.
1815 For these purposes an empty string (which can only occur at
1816 the end of one or both version strings being compared) counts
1821 These two steps (comparing and removing initial non-digit
1822 strings and initial digit strings) are repeated until a
1823 difference is found or both strings are exhausted.
1827 Note that the purpose of epochs is to allow us to leave behind
1828 mistakes in version numbering, and to cope with situations
1829 where the version numbering scheme changes. It is
1830 <em>not</em> intended to cope with version numbers containing
1831 strings of letters which the package management system cannot
1832 interpret (such as <tt>ALPHA</tt> or <tt>pre-</tt>), or with
1833 silly orderings (the author of this manual has heard of a
1834 package whose versions went <tt>1.1</tt>, <tt>1.2</tt>,
1835 <tt>1.3</tt>, <tt>1</tt>, <tt>2.1</tt>, <tt>2.2</tt>,
1836 <tt>2</tt> and so forth).
1840 If an upstream package has problematic version numbers they
1841 should be converted to a sane form for use in the
1842 <tt>Version</tt> field.
1846 <heading>Version numbers based on dates</heading>
1848 In general, Debian packages should use the same version
1849 numbers as the upstream sources.</p>
1852 However, in some cases where the upstream version number is
1853 based on a date (e.g., a development "snapshot" release) the
1854 package management system cannot handle these version
1855 numbers without epochs. For example, dpkg will consider
1856 "96May01" to be greater than "96Dec24".</p>
1859 To prevent having to use epochs for every new upstream
1860 version, the version number should be changed to the
1861 following format in such cases: "19960501", "19961224". It
1862 is up to the maintainer whether he/she wants to bother the
1863 upstream maintainer to change the version numbers upstream,
1867 Note that other version formats based on dates which are
1868 parsed correctly by the package management system should
1869 <em>not</em> be changed.</p>
1872 Native Debian packages (i.e., packages which have been
1873 written especially for Debian) whose version numbers include
1874 dates should always use the "YYYYMMDD" format.</p>
1878 <chapt id="miscellaneous"><heading>Packaging Considerations</heading>
1880 <sect id="timestamps"><heading>Time Stamps</heading>
1882 Maintainers should preserve the modification times of the
1883 upstream source files in a package, as far as is reasonably
1886 The rationale is that there is some information conveyed
1887 by knowing the age of the file, for example, you could
1888 recognize that some documentation is very old by looking
1889 at the modification time, so it would be nice if the
1890 modification time of the upstream source would be
1897 <sect id="debianrules"><heading><file>debian/rules</file> - the
1898 main building script</heading>
1901 This file must be an executable makefile, and contains the
1902 package-specific recipes for compiling the package and
1903 building binary package(s) from the source.
1907 It must start with the line <tt>#!/usr/bin/make -f</tt>,
1908 so that it can be invoked by saying its name rather than
1909 invoking <prgn>make</prgn> explicitly.
1913 Since an interactive <file>debian/rules</file> script makes it
1914 impossible to auto-compile that package and also makes it
1915 hard for other people to reproduce the same binary
1916 package, all <em>required targets</em> MUST be
1917 non-interactive. At a minimum, required targets are the
1918 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
1919 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>,
1920 <em>binary-indep</em>, and <em>build</em>. It also follows
1921 that any target that these targets depend on must also be
1926 The required and optional targets are as follows:
1928 <tag><tt>build</tt>, <tt>build-arch</tt> (optional),
1929 <tt>build-indep</tt> (optional)</tag>
1932 The <tt>build</tt> target should perform all
1933 non-interactive configuration and compilation of the
1934 package. If a package has an interactive pre-build
1935 configuration routine, the Debianized source package
1936 must either be built after this has taken place (so
1937 that the binary package can be built without rerunning
1938 the configuration) or the configuration routine
1939 modified to become non-interactive. (The latter is
1940 preferable if there are architecture-specific features
1941 detected by the configuration routine.)
1945 For some packages, notably ones where the same
1946 source tree is compiled in different ways to produce
1947 two binary packages, the <tt>build</tt> target
1948 does not make much sense. For these packages it is
1949 good enough to provide two (or more) targets
1950 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
1951 for each of the ways of building the package, and a
1952 <tt>build</tt> target that does nothing. The
1953 <tt>binary</tt> target will have to build the
1954 package in each of the possible ways and make the
1955 binary package out of each.
1959 The <tt>build</tt> target must not do anything
1960 that might require root privilege.
1964 The <tt>build</tt> target may need to run the
1965 <tt>clean</tt> target first - see below.
1969 When a package has a configuration and build routine
1970 which takes a long time, or when the makefiles are
1971 poorly designed, or when <tt>build</tt> needs to
1972 run <tt>clean</tt> first, it is a good idea to
1973 <tt>touch build</tt> when the build process is
1974 complete. This will ensure that if <tt>debian/rules
1975 build</tt> is run again it will not rebuild the whole
1978 Another common way to do this is for <tt>build</tt>
1979 to depend on <prgn>build-stamp</prgn> and to do
1980 nothing else, and for the <prgn>build-stamp</prgn>
1981 target to do the building and to <tt>touch
1982 build-stamp</tt> on completion. This is
1983 especially useful if the build routine creates a
1984 file or directory called <tt>build</tt>; in such a
1985 case, <tt>build</tt> will need to be listed as
1986 a phony target (i.e., as a dependency of the
1987 <tt>.PHONY</tt> target). See the documentation of
1988 <prgn>make</prgn> for more information on phony
1995 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
1996 <tt>binary-indep</tt>
2000 The <tt>binary</tt> target must be all that is
2001 necessary for the user to build the binary package(s)
2002 produced from this source package. All of these
2003 targets are required to be non-interactive. It is
2004 split into two parts: <prgn>binary-arch</prgn> builds
2005 the binary packages which are specific to a particular
2006 architecture, and <tt>binary-indep</tt> builds
2007 those which are not.
2010 <tt>binary</tt> may be (and commonly is) a target with
2011 no commands which simply depends on
2012 <tt>binary-arch</tt> and <tt>binary-indep</tt>.
2015 Both <tt>binary-*</tt> targets should depend on the
2016 <tt>build</tt> target, or on the appropriate
2017 <tt>build-arch</tt> or <tt>build-indep</tt> target, if
2018 provided, so that the package is built if it has not
2019 been already. It should then create the relevant
2020 binary package(s), using <prgn>dpkg-gencontrol</prgn> to
2021 make their control files and <prgn>dpkg-deb</prgn> to
2022 build them and place them in the parent of the top
2027 Both the <tt>binary-arch</tt> and
2028 <tt>binary-indep</tt> targets <em>must</em> exist.
2029 If one of them has nothing to do (which will always be
2030 the case if the source generates only a single binary
2031 package, whether architecture-dependent or not), it
2032 must still exist and must always succeed.
2036 The <tt>binary</tt> targets must be invoked as
2039 The <prgn>fakeroot</prgn> package often allows one
2040 to build a package correctly even without being
2047 <tag><tt>clean</tt></tag>
2050 This must undo any effects that the <tt>build</tt>
2051 and <tt>binary</tt> targets may have had, except
2052 that it should leave alone any output files created in
2053 the parent directory by a run of a <tt>binary</tt>
2054 target. This target must be non-interactive.
2058 If a <tt>build</tt> file is touched at the end of
2059 the <tt>build</tt> target, as suggested above, it
2060 should be removed as the first action that
2061 <tt>clean</tt> performs, so that running
2062 <tt>build</tt> again after an interrupted
2063 <tt>clean</tt> doesn't think that everything is
2068 The <tt>clean</tt> target may need to be
2069 invoked as root if <tt>binary</tt> has been
2070 invoked since the last <tt>clean</tt>, or if
2071 <tt>build</tt> has been invoked as root (since
2072 <tt>build</tt> may create directories, for
2077 <tag><tt>get-orig-source</tt> (optional)</tag>
2080 This target fetches the most recent version of the
2081 original source package from a canonical archive site
2082 (via FTP or WWW, for example), does any necessary
2083 rearrangement to turn it into the original source
2084 tar file format described below, and leaves it in the
2089 This target may be invoked in any directory, and
2090 should take care to clean up any temporary files it
2095 This target is optional, but providing it if
2096 possible is a good idea.
2102 The <tt>build</tt>, <tt>binary</tt> and
2103 <tt>clean</tt> targets must be invoked with the current
2104 directory being the package's top-level directory.
2109 Additional targets may exist in <file>debian/rules</file>,
2110 either as published or undocumented interfaces or for the
2111 package's internal use.
2115 The architectures we build on and build for are determined
2116 by <prgn>make</prgn> variables using the utility
2117 <prgn>dpkg-architecture</prgn>. You can determine the
2118 Debian architecture and the GNU style architecture
2119 specification string for the build machine (the machine type
2120 we are building on) as well as for the host machine (the
2121 machine type we are building for). Here is a list of
2122 supported <prgn>make</prgn> variables:
2123 <list compact="compact">
2125 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
2128 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
2129 specification string)</p>
2132 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of
2133 <tt>DEB_*_GNU_TYPE</tt>)</p>
2136 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
2137 <tt>DEB_*_GNU_TYPE</tt>)</p>
2139 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
2140 the build machine or <tt>HOST</tt> for specification of the
2145 Backward compatibility can be provided in the rules file
2146 by setting the needed variables to suitable default
2147 values; please refer to the documentation of
2148 <prgn>dpkg-architecture</prgn> for details.
2152 It is important to understand that the <tt>DEB_*_ARCH</tt>
2153 string only determines which Debian architecture we are
2154 building on or for. It should not be used to get the CPU
2155 or system information; the GNU style variables should be
2160 <sect id="dpkgchangelog"><heading><file>debian/changelog</file>
2164 This file records the changes to the Debian-specific parts of the
2167 Though there is nothing stopping an author who is also
2168 the Debian maintainer from using it for all their
2169 changes, it will have to be renamed if the Debian and
2170 upstream maintainers become different people. In such a
2171 case, however, it might be better to maintain the
2172 package as a non-native package.
2178 It has a special format which allows the package building
2179 tools to discover which version of the package is being
2180 built and find out other release-specific information.
2184 That format is a series of entries like this:
2185 <example compact="compact">
2186 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
2188 <p>[optional blank line(s), stripped]</p>
2190 * <var>change details</var>
2191 <var>more change details</var>
2193 <p>[blank line(s), included in output of dpkg-parsechangelog]</p>
2195 * <var>even more change details</var>
2197 <p>[optional blank line(s), stripped]</p>
2199 -- <var>maintainer name</var> <<var>email
2200 address</var>><var>[two spaces]</var> <var>date</var>
2205 <var>package</var> and <var>version</var> are the source
2206 package name and version number.
2210 <var>distribution(s)</var> lists the distributions where
2211 this version should be installed when it is uploaded - it
2212 is copied to the <tt>Distribution</tt> field in the
2213 <file>.changes</file> file. See <ref id="f-Distribution">.
2217 <var>urgency</var> is the value for the <tt>Urgency</tt>
2218 field in the <file>.changes</file> file for the upload. It is
2219 not possible to specify an urgency containing commas; commas
2220 are used to separate
2221 <tt><var>keyword</var>=<var>value</var></tt> settings in the
2222 <prgn>dpkg</prgn> changelog format (though there is
2223 currently only one useful <var>keyword</var>,
2224 <tt>urgency</tt>).<footnote>
2226 Recognised urgency values are <tt>low</tt>,
2227 <tt>medium</tt>, <tt>high</tt> and <tt>emergency</tt>.
2228 They have an effect on how quickly a package will be
2229 considered for inclusion into the <tt>testing</tt>
2230 distribution, and give an indication of the importance
2231 of any fixes included in this upload.
2237 The change details may in fact be any series of lines
2238 starting with at least two spaces, but conventionally each
2239 change starts with an asterisk and a separating space and
2240 continuation lines are indented so as to bring them in
2241 line with the start of the text above. Blank lines may be
2242 used here to separate groups of changes, if desired.
2246 If this upload resolves bugs recorded in the Bug Tracking
2247 System (BTS), they may be automatically closed on the
2248 inclusion of this package into the Debian archive by
2249 including the string: <tt>closes: Bug#<var>nnnnn</var></tt>
2250 in the change details.<footnote>
2252 To be precise, the string should match the following
2253 Perl regular expression:
2255 /closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*/i
2257 Then all of the bug numbers listed will be closed by the
2258 archive maintenance script (<prgn>katie</prgn>), or in
2259 the case of an NMU, marked as fixed.
2265 The maintainer name and email address used in the changelog
2266 should be the details of the person uploading <em>this</em>
2267 version. They are <em>not</em> necessarily those of the
2268 usual package maintainer. The information here will be
2269 copied to the <tt>Changed-By</tt> field in the
2270 <tt>.changes</tt> file, and then later used to send an
2271 acknowledgement when the upload has been installed.
2275 The <var>date</var> should be in RFC822 format<footnote>
2277 This is generated by the <prgn>822-date</prgn>
2280 </footnote>; it should include the time zone specified
2281 numerically, with the time zone name or abbreviation
2282 optionally present as a comment in parentheses.
2286 The first "title" line with the package name should start
2287 at the left hand margin; the "trailer" line with the
2288 maintainer and date details should be preceded by exactly
2289 one space. The maintainer details and the date must be
2290 separated by exactly two spaces.
2293 <sect1><heading>Defining alternative changelog formats</heading>
2296 It is possible to use a different format to the standard
2297 one, by providing a parser for the format you wish to
2301 A changelog parser must not interact with the user at
2307 <!-- FIXME: section pkg-srcsubstvars is the same as srcsubstvars -->
2309 <sect id="srcsubstvars"><heading><file>debian/substvars</file>
2310 and variable substitutions </heading>
2313 When <prgn>dpkg-gencontrol</prgn>,
2314 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
2315 generate control files they perform variable substitutions
2316 on their output just before writing it. Variable
2317 substitutions have the form <tt>${<var>variable</var>}</tt>.
2318 The optional file <file>debian/substvars</file> contains
2319 variable substitutions to be used; variables can also be set
2320 directly from <file>debian/rules</file> using the <tt>-V</tt>
2321 option to the source packaging commands, and certain
2322 predefined variables are also available.
2326 The <file>debian/substvars</file> file is usually generated and
2327 modified dynamically by <file>debian/rules</file> targets, in
2328 which case it must be removed by the <tt>clean</tt> target.
2332 See <manref name="dpkg-source" section="1"> for full
2333 details about source variable substitutions, including the
2334 format of <file>debian/substvars</file>.</p>
2337 <sect id="debianfiles"><heading><file>debian/files</file>
2341 This file is not a permanent part of the source tree; it
2342 is used while building packages to record which files are
2343 being generated. <prgn>dpkg-genchanges</prgn> uses it
2344 when it generates a <file>.changes</file> file.
2348 It should not exist in a shipped source package, and so it
2349 (and any backup files or temporary files such as
2350 <file>files.new</file><footnote>
2352 <file>files.new</file> is used as a temporary file by
2353 <prgn>dpkg-gencontrol</prgn> and
2354 <prgn>dpkg-distaddfile</prgn> - they write a new
2355 version of <tt>files</tt> here before renaming it,
2356 to avoid leaving a corrupted copy if an error
2359 </footnote>) should be removed by the
2360 <tt>clean</tt> target. It may also be wise to
2361 ensure a fresh start by emptying or removing it at the
2362 start of the <tt>binary</tt> target.
2366 When <prgn>dpkg-gencontrol</prgn> is run for a binary
2367 package, it adds an entry to <file>debian/files</file> for the
2368 <file>.deb</file> file that will be created when <tt>dpkg-deb
2369 --build</tt> is run for that binary package. So for most
2370 packages all that needs to be done with this file is to
2371 delete it in the <tt>clean</tt> target.
2375 If a package upload includes files besides the source
2376 package and any binary packages whose control files were
2377 made with <prgn>dpkg-gencontrol</prgn> then they should be
2378 placed in the parent of the package's top-level directory
2379 and <prgn>dpkg-distaddfile</prgn> should be called to add
2380 the file to the list in <file>debian/files</file>.</p>
2383 <sect id="restrictions"><heading>Restrictions on objects in source packages
2387 The source package may not contain any hard links<footnote>
2389 This is not currently detected when building source
2390 packages, but only when extracting
2394 Hard links may be permitted at some point in the
2395 future, but would require a fair amount of
2398 </footnote>, device special files, sockets or setuid or
2399 setgid files.<footnote>
2401 Setgid directories are allowed.
2407 <sect id="descriptions"><heading>Descriptions of packages - the
2408 <tt>Description</tt> field</heading>
2411 The "Description" control file field consists of two parts,
2412 the synopsis or the short description, and the long description.
2413 The field's format is as follows:
2417 Description: <single line synopsis>
2418 <extended description over several lines>
2422 The description is intended to describe the program to a user
2423 who has never met it before so that they know whether they
2424 want to install it. It should also give information about the
2425 significant dependencies and conflicts between this package
2426 and others, so that the user knows why these dependencies and
2427 conflicts have been declared.
2431 Put important information first, both in the synopsis and
2432 extended description. Sometimes only the first part of the
2433 synopsis or of the description will be displayed. You can
2434 assume that there will usually be a way to see the whole
2435 extended description.
2438 <sect1 id="synopsis"><heading>The single line synopsis</heading>
2441 The single line synopsis should be kept brief - certainly
2442 under 80 characters.
2446 Do not include the package name in the synopsis line. The
2447 display software knows how to display this already, and you
2448 do not need to state it. Remember that in many situations
2449 the user may only see the synopsis line - make it as
2450 informative as you can.
2455 <sect1 id="extendeddesc"><heading>The extended description</heading>
2458 Do not try to continue the single line synopsis into the
2459 extended description. This will not work correctly when
2460 the full description is displayed, and makes no sense
2461 where only the summary (the single line synopsis) is
2466 The extended description should describe what the package
2467 does and how it relates to the rest of the system (in terms
2468 of, for example, which subsystem it is which part of).
2472 The description field needs to make sense to anyone, even
2473 people who have no idea about any of the things the
2474 package deals with.<footnote>
2475 The blurb that comes with a program in its
2476 announcements and/or <prgn>README</prgn> files is
2477 rarely suitable for use in a description. It is
2478 usually aimed at people who are already in the
2479 community where the package is used.
2484 The lines in the extended description can have these formats:
2490 Those starting with a single space are part of a paragraph.
2491 Successive lines of this form will be word-wrapped when
2492 displayed. The leading space will usually be stripped off.
2496 Those starting with two or more spaces. These will be
2497 displayed verbatim. If the display cannot be panned
2498 horizontally, the displaying program will linewrap them "hard"
2499 (i.e., without taking account of word breaks). If it can they
2500 will be allowed to trail off to the right. None, one or two
2501 initial spaces may be deleted, but the number of spaces
2502 deleted from each line will be the same (so that you can have
2503 indenting work correctly, for example).
2507 Those containing a single space followed by a single full stop
2508 character. These are rendered as blank lines. This is the
2509 <em>only</em> way to get a blank line<footnote>
2510 Completely empty lines will not be rendered as blank lines.
2511 Instead, they will cause the parser to think you're starting
2512 a whole new record in the control file, and will therefore
2513 likely abort with an error.
2518 Those containing a space, a full stop and some more characters.
2519 These are for future expansion. Do not use them.
2525 Do not use tab characters. Their effect is not predictable.
2535 <chapt id="maintainerscripts"><heading>Package maintainer scripts
2536 and installation procedure
2539 <sect><heading>Introduction to package maintainer scripts
2543 It is possible to supply scripts as part of a package which
2544 the package management system will run for you when your
2545 package is installed, upgraded or removed.
2549 These scripts are the files <prgn>preinst</prgn>,
2550 <prgn>postinst</prgn>, <prgn>prerm</prgn> and <prgn>postrm</prgn> in the
2551 control area of the package. They must be proper executable
2552 files; if they are scripts (which is recommended), they must
2553 start with the usual <tt>#!</tt> convention. They should be
2554 readable and executable by anyone, and not world-writable.
2558 The package management system looks at the exit status from
2559 these scripts. It is important that they exit with a
2560 non-zero status if there is an error, so that the package
2561 management system can stop its processing. For shell
2562 scripts this means that you <em>almost always</em> need to
2563 use <tt>set -e</tt> (this is usually true when writing shell
2564 scripts, in fact). It is also important, of course, that
2565 they don't exit with a non-zero status if everything went
2570 When a package is upgraded a combination of the scripts from
2571 the old and new packages is called during the upgrade
2572 procedure. If your scripts are going to be at all
2573 complicated you need to be aware of this, and may need to
2574 check the arguments to your scripts.
2578 Broadly speaking the <prgn>preinst</prgn> is called before
2579 (a particular version of) a package is installed, and the
2580 <prgn>postinst</prgn> afterwards; the <prgn>prerm</prgn>
2581 before (a version of) a package is removed and the
2582 <prgn>postrm</prgn> afterwards.
2586 Programs called from maintainer scripts should not normally
2587 have a path prepended to them. Before installation is
2588 started, the package management system checks to see if the
2589 programs <prgn>ldconfig</prgn>,
2590 <prgn>start-stop-daemon</prgn>, <prgn>install-info</prgn>,
2591 and <prgn>update-rc.d</prgn> can be found via the
2592 <tt>PATH</tt> environment variable. Those programs, and any
2593 other program that one would expect to be on the
2594 <tt>PATH</tt>, should thus be invoked without an absolute
2595 pathname. Maintainer scripts should also not reset the
2596 <tt>PATH</tt>, though they might choose to modify it by
2597 prepending or appending package-specific directories. These
2598 considerations really apply to all shell scripts.</p>
2602 <heading>Maintainer scripts Idempotency</heading>
2605 It is necessary for the error recovery procedures that the
2606 scripts be idempotent. This means that if it is run
2607 successfully, and then it is called again, it doesn't bomb
2608 out or cause any harm, but just ensures that everything is
2609 the way it ought to be. If the first call failed, or
2610 aborted half way through for some reason, the second call
2611 should merely do the things that were left undone the first
2612 time, if any, and exit with a success status if everything
2615 This is so that if an error occurs, the user interrupts
2616 <prgn>dpkg</prgn> or some other unforeseen circumstance
2617 happens you don't leave the user with a badly-broken
2618 package when <prgn>dpkg</prgn> attempts to repeat the
2626 <heading>Controlling terminal for maintainer scripts</heading>
2629 The maintainer scripts are guaranteed to run with a
2630 controlling terminal and can interact with the user.
2631 If they need to prompt for passwords, do full-screen
2632 interaction or something similar you should do these
2633 things to and from <file>/dev/tty</file>, since
2634 <prgn>dpkg</prgn> will at some point redirect scripts'
2635 standard input and output so that it can log the
2636 installation process. Likewise, because these scripts
2637 may be executed with standard output redirected into a
2638 pipe for logging purposes, Perl scripts should set
2639 unbuffered output by setting <tt>$|=1</tt> so that the
2640 output is printed immediately rather than being
2645 Each script should return a zero exit status for
2646 success, or a nonzero one for failure.
2650 <sect id="mscriptsinstact"><heading>Summary of ways maintainer
2655 <list compact="compact">
2657 <p><var>new-preinst</var> <tt>install</tt></p>
2660 <p><var>new-preinst</var> <tt>install</tt>
2661 <var>old-version</var></p>
2664 <p><var>new-preinst</var> <tt>upgrade</tt>
2665 <var>old-version</var></p>
2668 <p><var>old-preinst</var> <tt>abort-upgrade</tt>
2669 <var>new-version</var>
2675 <list compact="compact">
2677 <p><var>postinst</var> <tt>configure</tt>
2678 <var>most-recently-configured-version</var></p>
2681 <p><var>old-postinst</var> <tt>abort-upgrade</tt>
2682 <var>new-version</var></p>
2685 <p><var>conflictor's-postinst</var> <tt>abort-remove</tt>
2686 <tt>in-favour</tt> <var>package</var>
2687 <var>new-version</var></p>
2691 <var>deconfigured's-postinst</var>
2692 <tt>abort-deconfigure</tt> <tt>in-favour</tt>
2693 <var>failed-install-package</var> <var>version</var>
2694 <tt>removing</tt> <var>conflicting-package</var>
2701 <list compact="compact">
2703 <p><var>prerm</var> <tt>remove</tt></p>
2706 <p><var>old-prerm</var> <tt>upgrade</tt>
2707 <var>new-version</var></p>
2710 <p><var>new-prerm</var> <tt>failed-upgrade</tt>
2711 <var>old-version</var></p>
2714 <p><var>conflictor's-prerm</var> <tt>remove</tt>
2715 <tt>in-favour</tt> <var>package</var>
2716 <var>new-version</var></p>
2720 <var>deconfigured's-prerm</var> <tt>deconfigure</tt>
2721 <tt>in-favour</tt> <var>package-being-installed</var>
2722 <var>version</var> <tt>removing</tt>
2723 <var>conflicting-package</var>
2730 <list compact="compact">
2732 <p><var>postrm</var> <tt>remove</tt></p>
2735 <p><var>postrm</var> <tt>purge</tt></p>
2739 <var>old-postrm</var> <tt>upgrade</tt>
2740 <var>new-version</var></p>
2743 <p><var>new-postrm</var> <tt>failed-upgrade</tt>
2744 <var>old-version</var></p>
2747 <p><var>new-postrm</var> <tt>abort-install</tt></p>
2750 <p><var>new-postrm</var> <tt>abort-install</tt>
2751 <var>old-version</var></p>
2754 <p><var>new-postrm</var> <tt>abort-upgrade</tt>
2755 <var>old-version</var></p>
2759 <var>disappearer's-postrm</var> <tt>disappear</tt>
2760 <var>overwriter</var>
2761 <var>overwriter-version</var></p></item>
2766 <sect id="unpackphase"><heading>Details of unpack phase of
2767 installation or upgrade
2771 The procedure on installation/upgrade/overwrite/disappear
2772 (i.e., when running <tt>dpkg --unpack</tt>, or the unpack
2773 stage of <tt>dpkg --install</tt>) is as follows. In each
2774 case, if a major error occurs (unless listed below) the
2775 actions are, in general, run backwards - this means that the
2776 maintainer scripts are run with different arguments in
2777 reverse order. These are the "error unwind" calls listed
2785 <p>If a version of the package is already
2787 <example compact="compact">
2788 <var>old-prerm</var> upgrade <var>new-version</var>
2793 If the script runs but exits with a non-zero
2794 exit status, <prgn>dpkg</prgn> will attempt:
2795 <example compact="compact">
2796 <var>new-prerm</var> failed-upgrade <var>old-version</var>
2798 Error unwind, for both the above cases:
2799 <example compact="compact">
2800 <var>old-postinst</var> abort-upgrade <var>new-version</var>
2808 <p>If a "conflicting" package is being removed at the same time:
2812 If any packages depended on that conflicting
2813 package and <tt>--auto-deconfigure</tt> is
2814 specified, call, for each such package:
2815 <example compact="compact">
2816 <var>deconfigured's-prerm</var> deconfigure \
2817 in-favour <var>package-being-installed</var> <var>version</var> \
2818 removing <var>conflicting-package</var> <var>version</var>
2821 <example compact="compact">
2822 <var>deconfigured's-postinst</var> abort-deconfigure \
2823 in-favour <var>package-being-installed-but-failed</var> <var>version</var> \
2824 removing <var>conflicting-package</var> <var>version</var>
2826 The deconfigured packages are marked as
2827 requiring configuration, so that if
2828 <tt>--install</tt> is used they will be
2829 configured again if possible.</p>
2832 <p>To prepare for removal of the conflicting package, call:
2833 <example compact="compact">
2834 <var>conflictor's-prerm</var> remove \
2835 in-favour <var>package</var> <var>new-version</var>
2838 <example compact="compact">
2839 <var>conflictor's-postinst</var> abort-remove \
2840 in-favour <var>package</var> <var>new-version</var>
2851 <p>If the package is being upgraded, call:
2852 <example compact="compact">
2853 <var>new-preinst</var> upgrade <var>old-version</var>
2858 Otherwise, if the package had some configuration
2859 files from a previous version installed (i.e., it
2860 is in the "configuration files only" state):
2861 <example compact="compact">
2862 <var>new-preinst</var> install <var>old-version</var>
2866 <p>Otherwise (i.e., the package was completely purged):
2867 <example compact="compact">
2868 <var>new-preinst</var> install
2870 Error unwind actions, respectively:
2871 <example compact="compact">
2872 <var>new-postrm</var> abort-upgrade <var>old-version</var>
2873 <var>new-postrm</var> abort-install <var>old-version</var>
2874 <var>new-postrm</var> abort-install
2883 The new package's files are unpacked, overwriting any
2884 that may be on the system already, for example any
2885 from the old version of the same package or from
2886 another package. Backups of the old files are kept
2887 temporarily, and if anything goes wrong the package
2888 management system will attempt to put them back as
2889 part of the error unwind.
2893 It is an error for a package to contains files which
2894 are on the system in another package, unless
2895 <tt>Replaces</tt> is used (see <ref id="replaces">).
2897 The following paragraph is not currently the case:
2898 Currently the <tt>- - force-overwrite</tt> flag is
2899 enabled, downgrading it to a warning, but this may not
2905 It is a more serious error for a package to contain a
2906 plain file or other kind of non-directory where another
2907 package has a directory (again, unless
2908 <tt>Replaces</tt> is used). This error can be
2909 overridden if desired using
2910 <tt>--force-overwrite-dir</tt>, but this is not
2915 Packages which overwrite each other's files produce
2916 behavior which, though deterministic, is hard for the
2917 system administrator to understand. It can easily
2918 lead to "missing" programs if, for example, a package
2919 is installed which overwrites a file from another
2920 package, and is then removed again.<footnote>
2922 Part of the problem is due to what is arguably a
2923 bug in <prgn>dpkg</prgn>.
2929 A directory will never be replaced by a symbolic link
2930 to a directory or vice versa; instead, the existing
2931 state (symlink or not) will be left alone and
2932 <prgn>dpkg</prgn> will follow the symlink if there is
2940 <p>If the package is being upgraded, call
2941 <example compact="compact">
2942 <var>old-postrm</var> upgrade <var>new-version</var>
2947 <p>If this fails, <prgn>dpkg</prgn> will attempt:
2948 <example compact="compact">
2949 <var>new-postrm</var> failed-upgrade <var>old-version</var>
2951 Error unwind, for both cases:
2952 <example compact="compact">
2953 <var>old-preinst</var> abort-upgrade <var>new-version</var>
2960 This is the point of no return - if
2961 <prgn>dpkg</prgn> gets this far, it won't back off
2962 past this point if an error occurs. This will
2963 leave the package in a fairly bad state, which
2964 will require a successful re-installation to clear
2965 up, but it's when <prgn>dpkg</prgn> starts doing
2966 things that are irreversible.
2971 Any files which were in the old version of the package
2972 but not in the new are removed.</p>
2975 <p>The new file list replaces the old.</p>
2978 <p>The new maintainer scripts replace the old.</p>
2982 <p>Any packages all of whose files have been overwritten during the
2983 installation, and which aren't required for
2984 dependencies, are considered to have been removed.
2985 For each such package
2988 <p><prgn>dpkg</prgn> calls:
2989 <example compact="compact">
2990 <var>disappearer's-postrm</var> disappear \
2991 <var>overwriter</var> <var>overwriter-version</var>
2996 <p>The package's maintainer scripts are removed.
3001 It is noted in the status database as being in a
3002 sane state, namely not installed (any conffiles
3003 it may have are ignored, rather than being
3004 removed by <prgn>dpkg</prgn>). Note that
3005 disappearing packages do not have their prerm
3006 called, because <prgn>dpkg</prgn> doesn't know
3007 in advance that the package is going to
3016 Any files in the package we're unpacking that are also
3017 listed in the file lists of other packages are removed
3018 from those lists. (This will lobotomize the file list
3019 of the "conflicting" package if there is one.)
3024 The backup files made during installation, above, are
3031 The new package's status is now sane, and recorded as
3036 Here is another point of no return - if the
3037 conflicting package's removal fails we do not unwind
3038 the rest of the installation; the conflicting package
3039 is left in a half-removed limbo.
3045 If there was a conflicting package we go and do the
3046 removal actions (described below), starting with the
3047 removal of the conflicting package's files (any that
3048 are also in the package being installed have already
3049 been removed from the conflicting package's file list,
3050 and so do not get removed now).
3057 <sect id="configdetails"><heading>Details of configuration</heading>
3060 When we configure a package (this happens with <tt>dpkg
3061 --install</tt> and <tt>dpkg --configure</tt>), we first
3062 update any <tt>conffile</tt>s and then call:
3063 <example compact="compact">
3064 <var>postinst</var> configure <var>most-recently-configured-version</var>
3069 No attempt is made to unwind after errors during
3074 If there is no most recently configured version
3075 <prgn>dpkg</prgn> will pass a null argument; older versions
3076 of dpkg may pass <tt><unknown></tt> (including the
3077 angle brackets) in this case. Even older ones do not pass a
3078 second argument at all, under any circumstances.
3082 <sect id="removedetails"><heading>Details of removal and/or
3083 configuration purging</heading>
3089 <example compact="compact">
3090 <var>prerm</var> remove
3096 The package's files are removed (except <tt>conffile</tt>s).
3101 <example compact="compact">
3102 <var>postrm</var> remove
3108 All the maintainer scripts except the <prgn>postrm</prgn>
3113 If we aren't purging the package we stop here. Note
3114 that packages which have no <prgn>postrm</prgn> and no
3115 <tt>conffile</tt>s are automatically purged when
3116 removed, as there is no difference except for the
3117 <prgn>dpkg</prgn> status.</p>
3121 The <tt>conffile</tt>s and any backup files
3122 (<tt>~</tt>-files, <tt>#*#</tt> files,
3123 <tt>%</tt>-files, <tt>.dpkg-{old,new,tmp}</tt>, etc.)
3128 <example compact="compact">
3129 <var>postrm</var> purge
3134 <p>The package's file list is removed.</p>
3137 No attempt is made to unwind after errors during
3144 <chapt id="relationships"><heading>Declaring relationships between
3147 <sect id="depsyntax"><heading>Syntax of relationship fields
3151 These fields all have a uniform syntax. They are a list of
3152 package names separated by commas.
3156 In the <tt>Depends</tt>, <tt>Recommends</tt>,
3157 <tt>Suggests</tt>, <tt>Pre-Depends</tt>,
3158 <tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
3159 control file fields of the package, which declare
3160 dependencies on other packages, the package names listed may
3161 also include lists of alternative package names, separated
3162 by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
3163 if any one of the alternative packages is installed, that
3164 part of the dependency is considered to be satisfied.
3168 All of the fields except for <tt>Provides</tt> may restrict
3169 their applicability to particular versions of each named
3170 package. This is done in parentheses after each individual
3171 package name; the parentheses should contain a relation from
3172 the list below followed by a version number, in the format
3173 described in <ref id="versions">.
3177 The relations allowed are <tt><<</tt>, <tt><=</tt>,
3178 <tt>=</tt>, <tt>>=</tt> and <tt>>></tt> for
3179 strictly earlier, earlier or equal, exactly equal, later or
3180 equal and strictly later, respectively. The deprecated
3181 forms <tt><</tt> and <tt>></tt> were used to mean
3182 earlier/later or equal, rather than strictly earlier/later,
3183 so they should not appear in new packages (though
3184 <prgn>dpkg</prgn> still supports them).
3188 Whitespace may appear at any point in the version
3189 specification subject to the rules in <ref
3190 id="controlsyntax">, and must appear where it's necessary to
3191 disambiguate; it is not otherwise significant. For
3192 consistency and in case of future changes to
3193 <prgn>dpkg</prgn> it is recommended that a single space be
3194 used after a version relationship and before a version
3195 number; it is also conventional to put a single space after
3196 each comma, on either side of each vertical bar, and before
3197 each open parenthesis.
3201 For example, a list of dependencies might appear as:
3202 <example compact="compact">
3205 Depends: libc6 (>= 2.2.1), exim | mail-transport-agent
3210 All fields that specify build-time relationships
3211 (<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3212 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
3213 may be restricted to a certain set of architectures. This
3214 is indicated in brackets after each individual package name and
3215 the optional version specification. The brackets enclose a
3216 list of Debian architecture names separated by whitespace.
3217 Exclamation marks may be prepended to each of the names.
3218 (It is not permitted for some names to be prepended with
3219 exclamation marks and others not.) If the current Debian
3220 host architecture is not in this list and there are no
3221 exclamation marks in the list, or it is in the list with a
3222 prepended exclamation mark, the package name and the
3223 associated version specification are ignored completely for
3224 the purposes of defining the relationships.
3229 <example compact="compact">
3231 Build-Depends-Indep: texinfo
3232 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
3233 hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
3238 Note that the binary package relationship fields such as
3239 <tt>Depends</tt> appear in one of the binary package
3240 sections of the control file, whereas the build-time
3241 relationships such as <tt>Build-Depends</tt> appear in the
3242 source package section of the control file (which is the
3248 <heading>Binary Dependencies - <tt>Depends</tt>,
3249 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3250 <tt>Pre-Depends</tt>
3254 Packages can declare in their control file that they have
3255 certain relationships to other packages - for example, that
3256 they may not be installed at the same time as certain other
3257 packages, and/or that they depend on the presence of others.
3261 This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
3262 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt> and
3263 <tt>Conflicts</tt> control file fields.
3267 These six fields are used to declare a dependency
3268 relationship by one package on another. Except for
3269 <tt>Enhances</tt>, they appear in the depending (binary)
3270 package's control file. (<tt>Enhances</tt> appears in the
3271 recommending package's control file.)
3275 A <tt>Depends</tt> field takes effect <em>only</em> when a
3276 package is to be configured. It does not prevent a package
3277 being on the system in an unconfigured state while its
3278 dependencies are unsatisfied, and it is possible to replace
3279 a package whose dependencies are satisfied and which is
3280 properly installed with a different version whose
3281 dependencies are not and cannot be satisfied; when this is
3282 done the depending package will be left unconfigured (since
3283 attempts to configure it will give errors) and will not
3284 function properly. If it is necessary, a
3285 <tt>Pre-Depends</tt> field can be used, which has a partial
3286 effect even when a package is being unpacked, as explained
3287 in detail below. (The other three dependency fields,
3288 <tt>Recommends</tt>, <tt>Suggests</tt> and
3289 <tt>Enhances</tt>, are only used by the various front-ends
3290 to <prgn>dpkg</prgn> such as <prgn>dselect</prgn>.)
3294 For this reason packages in an installation run are usually
3295 all unpacked first and all configured later; this gives
3296 later versions of packages with dependencies on later
3297 versions of other packages the opportunity to have their
3298 dependencies satisfied.
3302 The <tt>Depends</tt> field thus allows package maintainers
3303 to impose an order in which packages should be configured.
3307 The meaning of the five dependency fields is as follows:
3309 <tag><tt>Depends</tt></tag>
3312 This declares an absolute dependency. A package will
3313 not be configured unless all of the packages listed in
3314 its <tt>Depends</tt> field have been correctly
3319 The <tt>Depends</tt> field should be used if the
3320 depended-on package is required for the depending
3321 package to provide a significant amount of
3325 The <tt>Depends</tt> field should also be used if the
3326 <prgn>postinst</prgn>, <prgn>prerm</prgn> or
3327 <prgn>postrm</prgn> scripts require the package to be
3328 present in order to run. Note, however, that the
3329 <prgn>postrm</prgn> cannot rely on any non-essential
3330 packages to be present during the <tt>purge</tt>
3334 <tag><tt>Recommends</tt></tag>
3336 <p>This declares a strong, but not absolute, dependency.
3340 The <tt>Recommends</tt> field should list packages
3341 that would be found together with this one in all but
3342 unusual installations.</p>
3345 <tag><tt>Suggests</tt></tag>
3348 This is used to declare that one package may be more
3349 useful with one or more others. Using this field
3350 tells the packaging system and the user that the
3351 listed packages are related to this one and can
3352 perhaps enhance its usefulness, but that installing
3353 this one without them is perfectly reasonable.
3357 <tag><tt>Enhances</tt></tag>
3360 This field is similar to Suggests but works in the
3361 opposite direction. It is used to declare that a
3362 package can enhance the functionality of another
3367 <tag><tt>Pre-Depends</tt></tag>
3370 This field is like <tt>Depends</tt>, except that it
3371 also forces <prgn>dpkg</prgn> to complete installation
3372 of the packages named before even starting the
3373 installation of the package which declares the
3374 pre-dependency, as follows:
3378 When a package declaring a pre-dependency is about to
3379 be <em>unpacked</em> the pre-dependency can be
3380 satisfied if the depended-on package is either fully
3381 configured, <em>or even if</em> the depended-on
3382 package(s) are only unpacked or half-configured,
3383 provided that they have been configured correctly at
3384 some point in the past (and not removed or partially
3385 removed since). In this case, both the
3386 previously-configured and currently unpacked or
3387 half-configured versions must satisfy any version
3388 clause in the <tt>Pre-Depends</tt> field.
3392 When the package declaring a pre-dependency is about
3393 to be <em>configured</em>, the pre-dependency will be
3394 treated as a normal <tt>Depends</tt>, that is, it will
3395 be considered satisfied only if the depended-on
3396 package has been correctly configured.
3400 <tt>Pre-Depends</tt> should be used sparingly,
3401 preferably only by packages whose premature upgrade or
3402 installation would hamper the ability of the system to
3403 continue with any upgrade that might be in progress.
3407 <tt>Pre-Depends</tt> are also required if the
3408 <prgn>preinst</prgn> script depends on the named
3409 package. It is best to avoid this situation if
3415 When selecting which level of dependency to use you should
3416 consider how important the depended-on package is to the
3417 functionality of the one declaring the dependency. Some
3418 packages are composed of components of varying degrees of
3419 importance. Such a package should list using
3420 <tt>Depends</tt> the package(s) which are required by the
3421 more important components. The other components'
3422 requirements may be mentioned as Suggestions or
3423 Recommendations, as appropriate to the components' relative
3428 <sect id="conflicts"><heading>Conflicting binary packages -
3429 <tt>Conflicts</tt></heading>
3432 When one binary package declares a conflict with another
3433 using a <tt>Conflicts</tt> field, <prgn>dpkg</prgn> will
3434 refuse to allow them to be installed on the system at the
3439 If one package is to be installed, the other must be removed
3440 first - if the package being installed is marked as
3441 replacing (see <ref id="replaces">) the one on the system,
3442 or the one on the system is marked as deselected, or both
3443 packages are marked <tt>Essential</tt>, then
3444 <prgn>dpkg</prgn> will automatically remove the package
3445 which is causing the conflict, otherwise it will halt the
3446 installation of the new package with an error. This
3447 mechanism is specifically designed to produce an error when
3448 the installed package is <tt>Essential</tt>, but the new
3453 A package will not cause a conflict merely because its
3454 configuration files are still installed; it must be at least
3459 A special exception is made for packages which declare a
3460 conflict with their own package name, or with a virtual
3461 package which they provide (see below): this does not
3462 prevent their installation, and allows a package to conflict
3463 with others providing a replacement for it. You use this
3464 feature when you want the package in question to be the only
3465 package providing some feature.
3469 A <tt>Conflicts</tt> entry should almost never have an
3470 "earlier than" version clause. This would prevent
3471 <prgn>dpkg</prgn> from upgrading or installing the package
3472 which declared such a conflict until the upgrade or removal
3473 of the conflicted-with package had been completed.
3477 <sect id="virtual"><heading>Virtual packages - <tt>Provides</tt>
3481 As well as the names of actual ("concrete") packages, the
3482 package relationship fields <tt>Depends</tt>,
3483 <tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
3484 <tt>Pre-Depends</tt>, <tt>Conflicts</tt>,
3485 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3486 <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>
3487 may mention "virtual packages".
3491 A <em>virtual package</em> is one which appears in the
3492 <tt>Provides</tt> control file field of another package.
3493 The effect is as if the package(s) which provide a
3494 particular virtual package name had been listed by name
3495 everywhere the virtual package name appears. (See also <ref
3500 If there are both concrete and virtual packages of the same
3501 name, then the dependency may be satisfied (or the conflict
3502 caused) by either the concrete package with the name in
3503 question or any other concrete package which provides the
3504 virtual package with the name in question. This is so that,
3505 for example, supposing we have
3506 <example compact="compact">
3510 and someone else releases an enhanced version of the
3511 <tt>bar</tt> package (for example, a non-US variant), they
3513 <example compact="compact">
3517 and the <tt>bar-plus</tt> package will now also satisfy the
3518 dependency for the <tt>foo</tt> package.
3522 If a dependency or a conflict has a version number attached
3523 then only real packages will be considered to see whether
3524 the relationship is satisfied (or the prohibition violated,
3525 for a conflict) - it is assumed that a real package which
3526 provides the virtual package is not of the "right" version.
3527 So, a <tt>Provides</tt> field may not contain version
3528 numbers, and the version number of the concrete package
3529 which provides a particular virtual package will not be
3530 looked at when considering a dependency on or conflict with
3531 the virtual package name.
3535 It is likely that the ability will be added in a future
3536 release of <prgn>dpkg</prgn> to specify a version number for
3537 each virtual package it provides. This feature is not yet
3538 present, however, and is expected to be used only
3543 If you want to specify which of a set of real packages
3544 should be the default to satisfy a particular dependency on
3545 a virtual package, you should list the real package as an
3546 alternative before the virtual one.
3551 <sect id="replaces"><heading>Overwriting files and replacing
3552 packages - <tt>Replaces</tt></heading>
3555 Packages can declare in their control file that they should
3556 overwrite files in certain other packages, or completely
3557 replace other packages. The <tt>Replaces</tt> control file
3558 field has these two distinct purposes.
3561 <sect1><heading>Overwriting files in other packages</heading>
3564 Firstly, as mentioned before, it is usually an error for a
3565 package to contain files which are on the system in
3570 However, if the overwriting package declares that it
3571 <tt>Replaces</tt> the one containing the file being
3572 overwritten, then <prgn>dpkg</prgn> will replace the file
3573 from the old package with that from the new. The file
3574 will no longer be listed as "owned" by the old package.
3578 If a package is completely replaced in this way, so that
3579 <prgn>dpkg</prgn> does not know of any files it still
3580 contains, it is considered to have "disappeared". It will
3581 be marked as not wanted on the system (selected for
3582 removal) and not installed. Any <tt>conffile</tt>s
3583 details noted for the package will be ignored, as they
3584 will have been taken over by the overwriting package. The
3585 package's <prgn>postrm</prgn> script will be run with a
3586 special argument to allow the package to do any final
3587 cleanup required. See <ref id="mscriptsinstact">.
3591 If an installed package, <tt>foo</tt> say, declares that
3592 it replaces another, <tt>bar</tt>, and an attempt is made
3593 to install <tt>bar</tt>, <prgn>dpkg</prgn> will discard
3594 files in the <tt>bar</tt> package which would overwrite
3595 those already present in <tt>foo</tt>. This is so that
3596 you can install an older version of a package without
3601 For this usage of <tt>Replaces</tt>, virtual packages (see
3602 <ref id="virtual">) are not considered when looking at a
3603 <tt>Replaces</tt> field - the packages declared as being
3604 replaced must be mentioned by their real names.
3608 Furthermore, this usage of <tt>Replaces</tt> only takes
3609 effect when both packages are at least partially on the
3610 system at once, so that it can only happen if they do not
3611 conflict or if the conflict has been overridden.
3616 <sect1><heading>Replacing whole packages, forcing their
3620 Secondly, <tt>Replaces</tt> allows the packaging system to
3621 resolve which package should be removed when there is a
3622 conflict - see <ref id="conflicts">. This usage only
3623 takes effect when the two packages <em>do</em> conflict,
3624 so that the two usages of this field do not interfere with
3629 In this situation, the package declared as being replaced
3630 can be a virtual package, so for example, all mail
3631 transport agents (MTAs) would have the following fields in
3632 their control files:
3633 <example compact="compact">
3634 Provides: mail-transport-agent
3635 Conflicts: mail-transport-agent
3636 Replaces: mail-transport-agent
3638 ensuring that only one MTA can be installed at any one
3643 <sect><heading>Relationships between source and binary packages -
3644 <tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
3645 <tt>Build-Conflicts</tt>, <tt>Build-Conflicts-Indep</tt>
3649 Source packages that require certain binary packages to be
3650 installed or absent at the time of building the package
3651 can declare relationships to those binary packages.
3655 This is done using the <tt>Build-Depends</tt>,
3656 <tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
3657 <tt>Build-Conflicts-Indep</tt> control file fields.
3661 Build-dependencies on "build-essential" binary packages can be
3662 omitted. Please see <ref id="pkg-relations"> for more information.
3666 The dependencies and conflicts they define must be satisfied
3667 (as defined earlier for binary packages) in order to invoke
3668 the targets in <tt>debian/rules</tt>, as follows:<footnote>
3670 If you make "build-arch" or "binary-arch", you need
3671 Build-Depends. If you make "build-indep" or
3672 "binary-indep", you need Build-Depends and
3673 Build-Depends-Indep. If you make "build" or "binary",
3677 There is no Build-Depends-Arch; the autobuilders will
3678 only need the Build-Depends if they know how to build
3679 only build-arch and binary-arch. Anyone building the
3680 build-indep/binary-indep targets is basically assumed to
3681 be building the whole package and so installs all build
3685 The purpose of the original split, I recall, was so that
3686 the autobuilders wouldn't need to install extra packages
3687 needed only for the binary-indep targets. But without a
3688 build-arch/build-indep split, this didn't work, since
3689 most of the work is done in the build target, not in the
3695 <tag><tt>Build-Depends</tt>, <tt>Build-Conflicts</tt></tag>
3698 The <tt>Build-Depends</tt> and
3699 <tt>Build-Conflicts</tt> fields must be satisfied when
3700 any of the following targets is invoked:
3701 <tt>build</tt>, <tt>clean</tt>, <tt>binary</tt>,
3702 <tt>binary-arch</tt>, <tt>build-arch</tt>,
3703 <tt>build-indep</tt> and <tt>binary-indep</tt>.
3706 <tag><tt>Build-Depends-Indep</tt>,
3707 <tt>Build-Conflicts-Indep</tt></tag>
3710 The <tt>Build-Depends-Indep</tt> and
3711 <tt>Build-Conflicts-Indep</tt> fields must be
3712 satisfied when any of the following targets is
3713 invoked: <tt>build</tt>, <tt>clean</tt>,
3714 <tt>build-indep</tt>, <tt>binary</tt> and
3715 <tt>binary-indep</tt>.
3726 <chapt id="conffiles"><heading>Configuration file handling
3730 This chapter has been superseded by <ref id="config-files">.
3734 <chapt id="sharedlibs"><heading>Shared libraries</heading>
3737 Packages containing shared libraries must be constructed with
3738 a little care to make sure that the shared library is always
3739 available. This is especially important for packages whose
3740 shared libraries are vitally important, such as the C library
3741 (currently <tt>libc6</tt>).
3745 Packages involving shared libraries should be split up into
3746 several binary packages. This section mostly deals with how
3747 this separation is to be accomplished; rules for files within
3748 the shared library packages are in <ref id="libraries"> instead.
3751 <sect id="sharedlibs-runtime">
3752 <heading>Run-time shared libraries</heading>
3755 The run-time shared library needs to be placed in a package called
3756 <package><var>libraryname</var><var>soversion</var></package>, where
3757 <file><var>soversion</var></file> is the version number in the
3758 soname of the shared library<footnote>
3760 The soname is the shared object name: it's the thing
3761 that has to match exactly between building an executable
3762 and running it for the dynamic linker to be able run the
3763 program. For example, if the soname of the library is
3764 <file>libfoo.so.6</file>, the library package would be
3765 called <file>libfoo6</file>.
3768 Alternatively, if it would be confusing to directly append
3769 <var>soversion</var> to <var>libraryname</var> (e.g. because
3770 <var>libraryname</var> itself ends in a number), you may use
3771 <package><var>libraryname</var>-<var>soversion</var></package> and
3772 <package><var>libraryname</var>-<var>soversion</var>-dev</package>
3777 If you have several shared libraries built from the same
3778 source tree you may lump them all together into a single
3779 shared library package, provided that you change all of
3780 their sonames at once (so that you don't get filename
3781 clashes if you try to install different versions of the
3782 combined shared libraries package).
3786 The package should install the shared libraries under
3787 their normal names. For example, the <package>libgdbmg1</package>
3788 package should install <file>libgdbm.so.1.7.3</file> as
3789 <file>/usr/lib/libgdbm.so.1.7.3</file>. The files should not be
3790 renamed or re-linked by any <prgn>prerm</prgn> or
3791 <prgn>postrm</prgn> scripts; <prgn>dpkg</prgn> will take care
3792 of renaming things safely without affecting running programs,
3793 and attempts to interfere with this are likely to lead to
3798 Shared libraries should not be installed executable, since
3799 the dynamic linker does not require this and trying to
3800 execute a shared library usually results in a core dump.
3804 The run-time library package should include the symbolic link that
3805 <prgn>ldconfig</prgn> would create for the shared libraries.
3806 For example, the <package>libgdbmg1</package> package should include
3807 a symbolic link from <file>/usr/lib/libgdbm.so.1</file> to
3808 <file>libgdbm.so.1.7.3</file>. This is needed so that the dynamic
3809 linker (for example <prgn>ld.so</prgn> or
3810 <prgn>ld-linux.so.*</prgn>) can find the library between the
3811 time that <prgn>dpkg</prgn> installs it and the time that
3812 <prgn>ldconfig</prgn> is run in the <prgn>postinst</prgn>
3815 The package management system requires the library to be
3816 placed before the symbolic link pointing to it in the
3817 <file>.deb</file> file. This is so that when
3818 <prgn>dpkg</prgn> comes to install the symlink
3819 (overwriting the previous symlink pointing at an older
3820 version of the library), the new shared library is already
3821 in place. In the past, this was achieved by creating the
3822 library in the temporary packaging directory before
3823 creating the symlink. Unfortunately, this was not always
3824 effective, since the building of the tar file in the
3825 <file>.deb</file> depended on the behavior of the underlying
3826 file system. Some file systems (such as reiserfs) reorder
3827 the files so that the order of creation is forgotten.
3828 Since version 1.7.0, <prgn>dpkg</prgn>
3829 reorders the files itself as necessary when building a
3830 package. Thus it is no longer important to concern
3831 oneself with the order of file creation.
3836 <sect1 id="ldconfig">
3837 <heading><tt>ldconfig</tt></heading>
3840 Any package installing shared libraries in one of the default
3841 library directories of the dynamic linker (which are currently
3842 <file>/usr/lib</file> and <file>/lib</file>) or a directory that is
3843 listed in <file>/etc/ld.so.conf</file><footnote>
3846 <list compact="compact">
3847 <item><p>/usr/X11R6/lib/Xaw3d</p></item>
3848 <item><p>/usr/local/lib</p></item>
3849 <item><p>/usr/lib/libc5-compat</p></item>
3850 <item><p>/lib/libc5-compat</p></item>
3851 <item><p>/usr/X11R6/lib</p></item>
3855 must use <prgn>ldconfig</prgn> to update the shared library
3860 The package must call <prgn>ldconfig</prgn> in the
3861 <prgn>postinst</prgn> script if the first argument is
3862 <tt>configure</tt>; the <prgn>postinst</prgn> script may
3863 optionally invoke <prgn>ldconfig</prgn> at other times. The
3864 package should call <prgn>ldconfig</prgn> in the
3865 <prgn>postrm</prgn> script if the first argument is
3866 <tt>remove</tt>. The maintainer scripts must not invoke
3867 <prgn>ldconfig</prgn> under any circumstances other than those
3868 described in this paragraph.<footnote>
3869 <p>During install or upgrade, the preinst is called before
3870 the new files are installed, so calling "ldconfig" is
3871 pointless. The preinst of an existing package can also be
3872 called if an upgrade fails. However, this happens during
3873 the critical time when a shared libs may exist on-disk
3874 under a temporary name. Thus, it is dangerous and
3875 forbidden by current policy to call "ldconfig" at this
3878 <p>When a package is installed or upgraded, "postinst
3879 configure" runs after the new files are safely on-disk.
3880 Since it is perfectly safe to invoke ldconfig
3881 unconditionally in a postinst, it is OK for a package to
3882 simply put ldconfig in its postinst without checking the
3883 argument. The postinst can also be called to recover from
3884 a failed upgrade. This happens before any new files are
3885 unpacked, so there is no reason to call "ldconfig" at this
3888 <p>For a package that is being removed, prerm is
3889 called with all the files intact, so calling ldconfig is
3890 useless. The other calls to "prerm" happen in the case of
3891 upgrade at a time when all the files of the old package
3892 are on-disk, so again calling "ldconfig" is pointless.
3894 <p>postrm, on the other hand, is called with the "remove"
3895 argument just after the files are removed, so this is the
3896 proper time to call "ldconfig" to notify the system of the
3897 fact shared libraries from the package are removed.
3898 The postrm can be called at several other times. At the
3899 time of "postrm purge", "postrm abort-install", or "postrm
3900 abort-upgrade", calling "ldconfig" is useless because the
3901 shared lib files are not on-disk. However, when "postrm"
3902 is invoked with arguments "upgrade", "failed-upgrade", or
3903 "disappear", a shared lib may exist on-disk under a
3912 <sect id="sharedlibs-runtime-progs">
3913 <heading>Run-time support programs</heading>
3916 If your package has some run-time support programs which use
3917 the shared library you must not put them in the shared
3918 library package. If you do that then you won't be able to
3919 install several versions of the shared library without
3920 getting filename clashes.
3924 Instead, either create another package for the runtime binaries
3925 (this package might typically be named
3926 <package><var>libraryname</var>-runtime</package>; note the absence
3927 of the <var>soversion</var> in the package name), or if the
3928 development package is small, include them in there.
3932 <sect id="sharedlibs-static">
3933 <heading>Static libraries</heading>
3936 The static library (<file><var>libraryname.a</var></file>)
3937 is usually provided in addition to the shared version.
3938 It is placed into the development package (see below).
3942 In some cases, it is acceptable for a library to be
3943 available in static form only; these cases include:
3945 <item>libraries for languages whose shared library support
3946 is immature or unstable</item>
3947 <item>libraries whose interfaces are in flux or under
3948 development (commonly the case when the library's
3949 major version number is zero, or where the ABI breaks
3950 across patchlevels)</item>
3951 <item>libraries which are explicitly intended to be
3952 available only in static form by their upstream
3957 <sect id="sharedlibs-dev">
3958 <heading>Development files</heading>
3961 The development files associated to a shared library need to be
3962 placed in a package called
3963 <package><var>libraryname</var><var>soversion</var>-dev</package>,
3964 or if you prefer only to support one development version at a
3965 time, <package><var>libraryname</var>-dev</package>.
3969 In case several development versions of a library exist, you may
3970 need to use <prgn>dpkg</prgn>'s Conflicts mechanism (see
3971 <ref id="conflicts">) to ensure that the user only installs one
3972 development version at a time (as different development versions are
3973 likely to have the same header files in them, which would cause a
3974 filename clash if both were installed).
3978 The development package should contain a symlink for the associated
3979 shared library without a version number. For example, the
3980 <package>libgdbmg1-dev</package> package should include a symlink
3981 from <file>/usr/lib/libgdbm.so</file> to
3982 <file>libgdbm.so.1.7.3</file>. This symlink is needed by the linker
3983 (<prgn>ld</prgn>) when compiling packages, as it will only look for
3984 <file>libgdbm.so</file> when compiling dynamically.
3988 <sect id="sharedlibs-intradeps">
3989 <heading>Dependencies between the packages of the same library</heading>
3992 Typically the development version should have an exact
3993 version dependency on the runtime library, to make sure that
3994 compilation and linking happens correctly. The
3995 <tt>${Source-Version}</tt> substitution variable can be
3996 useful for this purpose.
4000 <sect id="sharedlibs-shlibdeps">
4001 <heading>Dependencies between the library and other packages -
4002 the <tt>shlibs</tt> system</heading>
4005 If a package contains a binary or library which links to a
4006 shared library, we must ensure that when the package is
4007 installed on the system, all of the libraries needed are
4008 also installed. This requirement led to the creation of the
4009 <tt>shlibs</tt> system, which is very simple in its design:
4010 any package which <em>provides</em> a shared library also
4011 provides information on the package dependencies required to
4012 ensure the presence of this library, and any package which
4013 <em>uses</em> a shared library uses this information to
4014 determine the dependencies it requires. The files which
4015 contain the mapping from shared libraries to the necessary
4016 dependency information are called <file>shlibs</file> files.
4020 Thus, when a package is built which contains any shared
4021 libraries, it must provide a <file>shlibs</file> file for other
4022 packages to use, and when a package is built which contains
4023 any shared libraries or compiled binaries, it must run
4024 <prgn>dpkg-shlibdeps</prgn> on these to determine the
4025 libraries used and hence the dependencies needed by this
4028 In the past, the shared libraries linked to were
4029 determined by calling <prgn>ldd</prgn>, but now
4030 <prgn>objdump</prgn> is used to do this. The only
4031 change this makes to package building is that
4032 <prgn>dpkg-shlibdeps</prgn> must also be run on shared
4033 libraries, whereas in the past this was unnecessary.
4034 The rest of this footnote explains the advantage that
4039 We say that a binary <tt>foo</tt> <em>directly</em> uses
4040 a library <tt>libbar</tt> if it is explicitly linked
4041 with that library (that is, it uses the flag
4042 <tt>-lbar</tt> during the linking stage). Other
4043 libraries that are needed by <tt>libbar</tt> are linked
4044 <em>indirectly</em> to <tt>foo</tt>, and the dynamic
4045 linker will load them automatically when it loads
4046 <tt>libbar</tt>. A package should depend on
4047 the libraries it directly uses, and the dependencies for
4048 those libraries should automatically pull in the other
4053 Unfortunately, the <prgn>ldd</prgn> program shows both
4054 the directly and indirectly used libraries, meaning that
4055 the dependencies determined included both direct and
4056 indirect dependencies. The use of <prgn>objdump</prgn>
4057 avoids this problem by determining only the directly
4062 A good example of where this helps is the following. We
4063 could update <tt>libimlib</tt> with a new version that
4064 supports a new graphics format called dgf (but retaining
4065 the same major version number). If we used the old
4066 <prgn>ldd</prgn> method, every package that uses
4067 <tt>libimlib</tt> would need to be recompiled so it
4068 would also depend on <tt>libdgf</tt> or it wouldn't run
4069 due to missing symbols. However with the new system,
4070 packages using <tt>libimlib</tt> can rely on
4071 <tt>libimlib</tt> itself having the dependency on
4072 <tt>libdgf</tt> and so they would not need rebuilding.
4078 In the following sections, we will first describe where the
4079 various <tt>shlibs</tt> files are to be found, then how to
4080 use <prgn>dpkg-shlibdeps</prgn>, and finally the
4081 <tt>shlibs</tt> file format and how to create them if your
4082 package contains a shared library.
4086 <heading>The <tt>shlibs</tt> files present on the system</heading>
4089 There are several places where <tt>shlibs</tt> files are
4090 found. The following list gives them in the order in which
4091 they are read by <prgn>dpkg-shlibdeps</prgn>. (The first
4092 one which gives the required information is used.)
4098 <p><file>debian/shlibs.local</file></p>
4100 This lists overrides for this package. Its use is
4101 described below (see <ref id="shlibslocal">).
4106 <p><file>/etc/dpkg/shlibs.override</file></p>
4108 This lists global overrides. This list is normally
4109 empty. It is maintained by the local system
4115 <p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
4117 When packages are being built, any
4118 <file>debian/shlibs</file> files are copied into the
4119 control file area of the temporary build directory and
4120 given the name <file>shlibs</file>. These files give
4121 details of any shared libraries included in the
4124 An example may help here. Let us say that the
4125 source package <tt>foo</tt> generates two binary
4126 packages, <tt>libfoo2</tt> and
4127 <tt>foo-runtime</tt>. When building the binary
4128 packages, the two packages are created in the
4129 directories <file>debian/libfoo2</file> and
4130 <file>debian/foo-runtime</file> respectively.
4131 (<file>debian/tmp</file> could be used instead of one
4132 of these.) Since <tt>libfoo2</tt> provides the
4133 <tt>libfoo</tt> shared library, it will require a
4134 <tt>shlibs</tt> file, which will be installed in
4135 <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
4137 <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
4138 when <prgn>dpkg-shlibdeps</prgn> is run on the
4140 <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
4142 <file>debian/libfoo2/DEBIAN/shlibs</file> file to
4143 determine whether <tt>foo-prog</tt>'s library
4144 dependencies are satisfied by any of the libraries
4145 provided by <tt>libfoo2</tt>. For this reason,
4146 <prgn>dpkg-shlibdeps</prgn> must only be run once
4147 all of the individual binary packages'
4148 <tt>shlibs</tt> files have been installed into the
4156 <p><file>/var/lib/dpkg/info/*.shlibs</file></p>
4158 These are the <file>shlibs</file> files corresponding to
4159 all of the packages installed on the system, and are
4160 maintained by the relevant package maintainers.
4165 <p><file>/etc/dpkg/shlibs.default</file></p>
4167 This file lists any shared libraries whose packages
4168 have failed to provide correct <file>shlibs</file> files.
4169 It was used when the <file>shlibs</file> setup was first
4170 introduced, but it is now normally empty. It is
4171 maintained by the <tt>dpkg</tt> maintainer.
4179 <heading>How to use <prgn>dpkg-shlibdeps</prgn> and the
4180 <file>shlibs</file> files</heading>
4183 Put a call to <prgn>dpkg-shlibdeps</prgn> into your
4184 <file>debian/rules</file> file. If your package contains only
4185 compiled binaries and libraries (but no scripts), you can
4186 use a command such as:
4187 <example compact="compact">
4188 dpkg-shlibdeps debian/tmp/usr/bin/* debian/tmp/usr/sbin/* \
4189 debian/tmp/usr/lib/*
4191 Otherwise, you will need to explicitly list the compiled
4192 binaries and libraries.<footnote>
4194 If you are using <tt>debhelper</tt>, the
4195 <prgn>dh_shlibdeps</prgn> program will do this work for
4196 you. It will also correctly handle multi-binary
4203 This command puts the dependency information into the
4204 <file>debian/substvars</file> file, which is then used by
4205 <prgn>dpkg-gencontrol</prgn>. You will need to place a
4206 <tt>${shlib:Depends}</tt> variable in the <tt>Depends</tt>
4207 field in the control file for this to work.
4211 If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
4212 done. If it does complain you might need to create your own
4213 <file>debian/shlibs.local</file> file, as explained below (see
4214 <ref id="shlibslocal">).
4218 If you have multiple binary packages, you will need to call
4219 <prgn>dpkg-shlibdeps</prgn> on each one which contains
4220 compiled libraries or binaries. In such a case, you will
4221 need to use the <tt>-T</tt> option to the <tt>dpkg</tt>
4222 utilities to specify a different <file>substvars</file> file.
4223 For more details on this and other options, see <manref
4224 name="dpkg-shlibdeps" section="1">.
4229 <heading>The <file>shlibs</file> File Format</heading>
4232 Each <file>shlibs</file> file has the same format. Lines
4233 beginning with <tt>#</tt> are considered to be comments and
4234 are ignored. Each line is of the form:
4235 <example compact="compact">
4236 <var>library-name</var> <var>soname-version-number</var> <var>dependencies ...</var>
4241 We will explain this by reference to the example of the
4242 <tt>zlib1g</tt> package, which (at the time of writing)
4243 installs the shared library <file>/usr/lib/libz.so.1.1.3</file>.
4247 <var>library-name</var> is the name of the shared library,
4248 in this case <tt>libz</tt>. (This must match the name part
4249 of the soname, see below.)
4253 <var>soname-version-number</var> is the version part of the
4254 soname of the library. The soname is the thing that must
4255 exactly match for the library to be recognized by the
4256 dynamic linker, and is usually of the form
4257 <tt><var>name</var>.so.<var>major-version</var></tt>, in our
4258 example, <tt>libz.so.1</tt>.<footnote>
4260 This can be determined using the command
4261 <example compact="compact">
4262 objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
4266 The version part is the part which comes after
4267 <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
4271 <var>dependencies</var> has the same syntax as a dependency
4272 field in a binary package control file. It should give
4273 details of which packages are required to satisfy a binary
4274 built against the version of the library contained in the
4275 package. See <ref id="depsyntax"> for details.
4279 In our example, if the first version of the <tt>zlib1g</tt>
4280 package which contained a minor number of at least
4281 <tt>1.3</tt> was <var>1:1.1.3-1</var>, then the
4282 <tt>shlibs</tt> entry for this library could say:
4283 <example compact="compact">
4284 libz 1 zlib1g (>= 1:1.1.3)
4286 The version-specific dependency is to avoid warnings from
4287 the dynamic linker about using older shared libraries with
4293 <heading>Providing a <file>shlibs</file> file</heading>
4296 If your package provides a shared library, you should create
4297 a <file>shlibs</file> file following the format described above.
4298 It is usual to call this file <file>debian/shlibs</file> (but if
4299 you have multiple binary packages, you might want to call it
4300 <file>debian/shlibs.<var>package</var></file> instead). Then
4301 let <file>debian/rules</file> install it in the control area:
4302 <example compact="compact">
4303 install -m644 debian/shlibs debian/tmp/DEBIAN
4305 or, in the case of a multi-binary package:
4306 <example compact="compact">
4307 install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
4309 An alternative way of doing this is to create the
4310 <file>shlibs</file> file in the control area directly from
4311 <file>debian/rules</file> without using a <file>debian/shlibs</file>
4312 file at all,<footnote>
4314 This is what <prgn>dh_makeshlibs</prgn> in the
4315 <tt>debhelper</tt> suite does.
4318 since the <file>debian/shlibs</file> file itself is ignored by
4319 <prgn>dpkg-shlibdeps</prgn>.
4323 As <prgn>dpkg-shlibdeps</prgn> reads the
4324 <file>DEBIAN/shlibs</file> files in all of the binary packages
4325 being built from this source package, all of the
4326 <file>DEBIAN/shlibs</file> files should be installed before
4327 <prgn>dpkg-shlibdeps</prgn> is called on any of the binary
4332 <sect1 id="shlibslocal">
4333 <heading>Writing the <file>debian/shlibs.local</file> file</heading>
4336 This file is intended only as a <em>temporary</em> fix if
4337 your binaries or libraries depend on a library whose package
4338 does not yet provide a correct <file>shlibs</file> file.
4342 We will assume that you are trying to package a binary
4343 <tt>foo</tt>. When you try running
4344 <prgn>dpkg-shlibdeps</prgn> you get the following error
4345 message (<tt>-O</tt> displays the dependency information on
4346 <tt>stdout</tt> instead of writing it to
4347 <tt>debian/substvars</tt>, and the lines have been wrapped
4348 for ease of reading):
4349 <example compact="compact">
4350 $ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
4351 dpkg-shlibdeps: warning: unable to find dependency
4352 information for shared library libbar (soname 1,
4353 path /usr/lib/libbar.so.1, dependency field Depends)
4354 shlibs:Depends=libc6 (>= 2.2.2-2)
4356 You can then run <prgn>ldd</prgn> on the binary to find the
4357 full location of the library concerned:
4358 <example compact="compact">
4360 libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
4361 libc.so.6 => /lib/libc.so.6 (0x40032000)
4362 /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
4364 So the <prgn>foo</prgn> binary depends on the
4365 <prgn>libbar</prgn> shared library, but no package seems to
4366 provide a <file>*.shlibs</file> file handling
4367 <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
4368 determine the package responsible:
4369 <example compact="compact">
4370 $ dpkg -S /usr/lib/libbar.so.1
4371 bar1: /usr/lib/libbar.so.1
4372 $ dpkg -s bar1 | grep Version
4375 This tells us that the <tt>bar1</tt> package, version 1.0-1,
4376 is the one we are using. Now we can file a bug against the
4377 <tt>bar1</tt> package and create our own
4378 <file>debian/shlibs.local</file> to locally fix the problem.
4379 Including the following line into your
4380 <file>debian/shlibs.local</file> file:
4381 <example compact="compact">
4382 libbar 1 bar1 (>= 1.0-1)
4384 should allow the package build to work.
4388 As soon as the maintainer of <tt>bar1</tt> provides a
4389 correct <file>shlibs</file> file, you should remove this line
4390 from your <file>debian/shlibs.local</file> file. (You should
4391 probably also then have a versioned <tt>Build-Depends</tt>
4392 on <tt>bar1</tt> to help ensure that others do not have the
4393 same problem building your package.)
4401 <chapt id="opersys"><heading>The Operating System</heading>
4404 <heading>Filesystem hierarchy</heading>
4408 <heading>Filesystem Structure</heading>
4411 The location of all installed files and directories must
4412 comply with the Filesystem Hierarchy Standard (FHS),
4413 version 2.1, except where doing so would violate other
4414 terms of Debian Policy. The version of this document
4415 referred here can be found in the <tt>debian-policy</tt>
4417 <url id="http://www.debian.org/doc/packaging-manuals/fhs/"
4418 name="FHS (Debian copy)"> alongside this manual (or, if
4419 you have the <package>debian-policy</package> installed,
4421 id="file:///usr/share/doc/debian-policy/fhs/" name="FHS
4422 (local copy)">). The
4423 latest version, which may be a more recent version, may
4425 <url id="http://www.pathname.com/fhs/" name="FHS (upstream)">.
4426 Specific questions about following the standard may be
4427 asked on the <tt>debian-devel</tt> mailing list, or
4428 referred to the FHS mailing list (see the
4429 <url id="http://www.pathname.com/fhs/" name="FHS web site"> for
4435 <heading>Site-specific programs</heading>
4438 As mandated by the FHS, packages must not place any
4439 files in <file>/usr/local</file>, either by putting them in
4440 the file system archive to be unpacked by <prgn>dpkg</prgn>
4441 or by manipulating them in their maintainer scripts.
4445 However, the package may create empty directories below
4446 <file>/usr/local</file> so that the system administrator knows
4447 where to place site-specific files. These directories
4448 should be removed on package removal if they are
4453 Note, that this applies only to directories <em>below</em>
4454 <file>/usr/local</file>, not <em>in</em> <file>/usr/local</file>.
4455 Packages must not create sub-directories in the directory
4456 <file>/usr/local</file> itself, except those listed in FHS,
4457 section 4.5. However, you may create directories below
4458 them as you wish. You must not remove any of the
4459 directories listed in 4.5, even if you created them.
4463 Since <file>/usr/local</file> can be mounted read-only from a
4464 remote server, these directories must be created and
4465 removed by the <prgn>postinst</prgn> and <prgn>prerm</prgn>
4466 maintainer scripts and not be included in the
4467 <file>.deb</file> archive. These scripts must not fail if
4468 either of these operations fail.
4472 For example, the <tt>emacsen-common</tt> package could
4473 contain something like
4474 <example compact="compact">
4475 if [ ! -e /usr/local/share/emacs ]
4477 if mkdir /usr/local/share/emacs 2>/dev/null
4479 chown root:staff /usr/local/share/emacs
4480 chmod 2775 /usr/local/share/emacs
4484 in its <prgn>postinst</prgn> script, and
4485 <example compact="compact">
4486 rmdir /usr/local/share/emacs/site-lisp 2>/dev/null || true
4487 rmdir /usr/local/share/emacs 2>/dev/null || true
4489 in the <prgn>prerm</prgn> script. (Note that this form is
4490 used to ensure that if the script is interrupted, the
4491 directory <file>/usr/local/share/emacs</file> will still be
4496 If you do create a directory in <file>/usr/local</file> for
4497 local additions to a package, you should ensure that
4498 settings in <file>/usr/local</file> take precedence over the
4499 equivalents in <file>/usr</file>.
4503 However, because <file>/usr/local</file> and its contents are
4504 for exclusive use of the local administrator, a package
4505 must not rely on the presence or absence of files or
4506 directories in <file>/usr/local</file> for normal operation.
4510 The <file>/usr/local</file> directory itself and all the
4511 subdirectories created by the package should (by default) have
4512 permissions 2775 (group-writable and set-group-id) and be
4513 owned by <tt>root.staff</tt>.
4518 <heading>The system-wide mail directory</heading>
4520 The system-wide mail directory is <file>/var/mail</file>. This
4521 directory is part of the base system and should not owned
4522 by any particular mail agents. The use of the old
4523 location <file>/var/spool/mail</file> is deprecated, even
4524 though the spool may still be physically located there.
4525 To maintain partial upgrade compatibility for systems
4526 which have <file>/var/spool/mail</file> as their physical mail
4527 spool, packages using <file>/var/mail</file> must depend on
4528 either <package>libc6</package> (>= 2.1.3-13), or on
4529 <package>base-files</package> (>= 2.2.0), or on later
4530 versions of either one of these packages.
4536 <heading>Users and groups</heading>
4539 <heading>Introduction</heading>
4541 The Debian system can be configured to use either plain or
4546 Some user ids (UIDs) and group ids (GIDs) are reserved
4547 globally for use by certain packages. Because some
4548 packages need to include files which are owned by these
4549 users or groups, or need the ids compiled into binaries,
4550 these ids must be used on any Debian system only for the
4551 purpose for which they are allocated. This is a serious
4552 restriction, and we should avoid getting in the way of
4553 local administration policies. In particular, many sites
4554 allocate users and/or local system groups starting at 100.
4558 Apart from this we should have dynamically allocated ids,
4559 which should by default be arranged in some sensible
4560 order, but the behavior should be configurable.
4564 Packages other than <tt>base-passwd</tt> must not modify
4565 <file>/etc/passwd</file>, <file>/etc/shadow</file>,
4566 <file>/etc/group</file> or <file>/etc/gshadow</file>.
4571 <heading>UID and GID classes</heading>
4573 The UID and GID numbers are divided into classes as
4579 Globally allocated by the Debian project, the same
4580 on every Debian system. These ids will appear in
4581 the <file>passwd</file> and <file>group</file> files of all
4582 Debian systems, new ids in this range being added
4583 automatically as the <tt>base-passwd</tt> package is
4588 Packages which need a single statically allocated
4589 uid or gid should use one of these; their
4590 maintainers should ask the <tt>base-passwd</tt>
4598 Dynamically allocated system users and groups.
4599 Packages which need a user or group, but can have
4600 this user or group allocated dynamically and
4601 differently on each system, should use <tt>adduser
4602 --system</tt> to create the group and/or user.
4603 <prgn>adduser</prgn> will check for the existence of
4604 the user or group, and if necessary choose an unused
4605 id based on the ranges specified in
4606 <file>adduser.conf</file>.
4610 <tag>1000-29999:</tag>
4613 Dynamically allocated user accounts. By default
4614 <prgn>adduser</prgn> will choose UIDs and GIDs for
4615 user accounts in this range, though
4616 <file>adduser.conf</file> may be used to modify this
4621 <tag>30000-59999:</tag>
4626 <tag>60000-64999:</tag>
4629 Globally allocated by the Debian project, but only
4630 created on demand. The ids are allocated centrally
4631 and statically, but the actual accounts are only
4632 created on users' systems on demand.
4636 These ids are for packages which are obscure or
4637 which require many statically-allocated ids. These
4638 packages should check for and create the accounts in
4639 <file>/etc/passwd</file> or <file>/etc/group</file> (using
4640 <prgn>adduser</prgn> if it has this facility) if
4641 necessary. Packages which are likely to require
4642 further allocations should have a "hole" left after
4643 them in the allocation, to give them room to
4648 <tag>65000-65533:</tag>
4656 User <tt>nobody</tt>. The corresponding gid refers
4657 to the group <tt>nogroup</tt>.
4664 <tt>(uid_t)(-1) == (gid_t)(-1)</tt> <em>must
4665 not</em> be used, because it is the error return
4674 <sect id="sysvinit">
4675 <heading>System run levels and <file>init.d</file> scripts</heading>
4677 <sect1 id="/etc/init.d">
4678 <heading>Introduction</heading>
4681 The <file>/etc/init.d</file> directory contains the scripts
4682 executed by <prgn>init</prgn> at boot time and when the
4683 init state (or "runlevel") is changed (see <manref
4684 name="init" section="8">).
4688 There are at least two different, yet functionally
4689 equivalent, ways of handling these scripts. For the sake
4690 of simplicity, this document describes only the symbolic
4691 link method. However, it must not be assumed by maintainer
4692 scripts that this method is being used, and any automated
4693 manipulation of the various runlevel behaviours by
4694 maintainer scripts must be performed using
4695 <prgn>update-rc.d</prgn> as described below and not by
4696 manually installing or removing symlinks. For information
4697 on the implementation details of the other method,
4698 implemented in the <tt>file-rc</tt> package, please refer
4699 to the documentation of that package.
4703 These scripts are referenced by symbolic links in the
4704 <file>/etc/rc<var>n</var>.d</file> directories. When changing
4705 runlevels, <prgn>init</prgn> looks in the directory
4706 <file>/etc/rc<var>n</var>.d</file> for the scripts it should
4707 execute, where <tt><var>n</var></tt> is the runlevel that
4708 is being changed to, or <tt>S</tt> for the boot-up
4713 The names of the links all have the form
4714 <file>S<var>mm</var><var>script</var></file> or
4715 <file>K<var>mm</var><var>script</var></file> where
4716 <var>mm</var> is a two-digit number and <var>script</var>
4717 is the name of the script (this should be the same as the
4718 name of the actual script in <file>/etc/init.d</file>).
4722 When <prgn>init</prgn> changes runlevel first the targets
4723 of the links whose names start with a <tt>K</tt> are
4724 executed, each with the single argument <tt>stop</tt>,
4725 followed by the scripts prefixed with an <tt>S</tt>, each
4726 with the single argument <tt>start</tt>. (The links are
4727 those in the <file>/etc/rc<var>n</var>.d</file> directory
4728 corresponding to the new runlevel.) The <tt>K</tt> links
4729 are responsible for killing services and the <tt>S</tt>
4730 link for starting services upon entering the runlevel.
4734 For example, if we are changing from runlevel 2 to
4735 runlevel 3, init will first execute all of the <tt>K</tt>
4736 prefixed scripts it finds in <file>/etc/rc3.d</file>, and then
4737 all of the <tt>S</tt> prefixed scripts in that directory.
4738 The links starting with <tt>K</tt> will cause the
4739 referred-to file to be executed with an argument of
4740 <tt>stop</tt>, and the <tt>S</tt> links with an argument
4745 The two-digit number <var>mm</var> is used to determine
4746 the order in which to run the scripts: low-numbered links
4747 have their scripts run first. For example, the
4748 <tt>K20</tt> scripts will be executed before the
4749 <tt>K30</tt> scripts. This is used when a certain service
4750 must be started before another. For example, the name
4751 server <prgn>bind</prgn> might need to be started before
4752 the news server <prgn>inn</prgn> so that <prgn>inn</prgn>
4753 can set up its access lists. In this case, the script
4754 that starts <prgn>bind</prgn> would have a lower number
4755 than the script that starts <prgn>inn</prgn> so that it
4757 <example compact="compact">
4764 The two runlevels 0 (halt) and 6 (reboot) are slightly
4765 different. In these runlevels, the links with an
4766 <tt>S</tt> prefix are still called after those with a
4767 <tt>K</tt> prefix, but they too are called with the single
4768 argument <tt>stop</tt>.
4772 Also, if the script name ends <tt>.sh</tt>, the script
4773 will be sourced in runlevel <tt>S</tt> rather that being
4774 run in a forked subprocess, but will be explicitly run by
4775 <prgn>sh</prgn> in all other runlevels.
4780 <heading>Writing the scripts</heading>
4783 Packages that include daemons for system services should
4784 place scripts in <file>/etc/init.d</file> to start or stop
4785 services at boot time or during a change of runlevel.
4786 These scripts should be named
4787 <file>/etc/init.d/<var>package</var></file>, and they should
4788 accept one argument, saying what to do:
4791 <tag><tt>start</tt></tag>
4792 <item><p>start the service,</p></item>
4794 <tag><tt>stop</tt></tag>
4795 <item><p>stop the service,</p></item>
4797 <tag><tt>restart</tt></tag>
4798 <item><p>stop and restart the service if it's already
4799 running, otherwise start the service</p></item>
4801 <tag><tt>reload</tt></tag>
4802 <item><p>cause the configuration of the service to be
4803 reloaded without actually stopping and restarting
4804 the service,</p></item>
4806 <tag><tt>force-reload</tt></tag>
4807 <item><p>cause the configuration to be reloaded if the
4808 service supports this, otherwise restart the
4812 The <tt>start</tt>, <tt>stop</tt>, <tt>restart</tt>, and
4813 <tt>force-reload</tt> options should be supported by all
4814 scripts in <file>/etc/init.d</file>, the <tt>reload</tt>
4815 option is optional.</p>
4818 The <file>init.d</file> scripts should ensure that they will
4819 behave sensibly if invoked with <tt>start</tt> when the
4820 service is already running, or with <tt>stop</tt> when it
4821 isn't, and that they don't kill unfortunately-named user
4822 processes. The best way to achieve this is usually to use
4823 <prgn>start-stop-daemon</prgn>.</p>
4826 If a service reloads its configuration automatically (as
4827 in the case of <prgn>cron</prgn>, for example), the
4828 <tt>reload</tt> option of the <file>init.d</file> script
4829 should behave as if the configuration has been reloaded
4833 The <file>/etc/init.d</file> scripts must be treated as
4834 configuration files, either (if they are present in the
4835 package, that is, in the .deb file) by marking them as
4836 <tt>conffile</tt>s, or, (if they do not exist in the .deb)
4837 by managing them correctly in the maintainer scripts (see
4838 <ref id="config-files">). This is important since we want
4839 to give the local system administrator the chance to adapt
4840 the scripts to the local system, e.g., to disable a
4841 service without de-installing the package, or to specify
4842 some special command line options when starting a service,
4843 while making sure her changes aren't lost during the next
4848 These scripts should not fail obscurely when the
4849 configuration files remain but the package has been
4850 removed, as configuration files remain on the system after
4851 the package has been removed. Only when <prgn>dpkg</prgn>
4852 is executed with the <tt>--purge</tt> option will
4853 configuration files be removed. In particular, as the
4854 <file>/etc/init.d/<var>package</var></file> script itself is
4855 usually a <tt>conffile</tt>, it will remain on the system
4856 if the package is removed but not purged. Therefore, you
4857 should include a <tt>test</tt> statement at the top of the
4859 <example compact="compact">
4860 test -f <var>program-executed-later-in-script</var> || exit 0
4865 Often there are some variables in the <file>init.d</file>
4866 scripts whose values control the behaviour of the scripts,
4867 and which a system administrator is likely to want to
4868 change. As the scripts themselves are frequently
4869 <tt>conffile</tt>s, modifying them requires that the
4870 administrator merge in their changes each time the package
4871 is upgraded and the <tt>conffile</tt> changes. To ease
4872 the burden on the system administrator, such configurable
4873 values should not be placed directly in the script.
4874 Instead, they should be placed in a file in
4875 <file>/etc/default</file>, which typically will have the same
4876 base name as the <file>init.d</file> script. This extra file
4877 should be sourced by the script when the script runs. It
4878 must contain only variable settings and comments in POSIX
4879 <prgn>sh</prgn> format. It may either be a
4880 <tt>conffile</tt> or a configuration file maintained by
4881 the package maintainer scripts. See <ref id="config-files">
4886 To ensure that vital configurable values are always
4887 available, the <file>init.d</file> script should set default
4888 values for each of the shell variables it uses, either
4889 before sourcing the <file>/etc/default/</file> file or
4890 afterwards using something like the <tt>:
4891 ${VAR:=default}</tt> syntax. Also, the <file>init.d</file>
4892 script must behave sensibly and not fail if the
4893 <file>/etc/default</file> file is deleted.
4898 <heading>Interfacing with the initscript system</heading>
4901 Maintainers should use the abstraction layer provided by
4902 the <prgn>update-rc.d</prgn> and <prgn>invoke-rc.d</prgn>
4903 programs to deal with initscripts in their packages'
4904 scripts such as <prgn>postinst</prgn>, <prgn>prerm</prgn>
4905 and <prgn>postrm</prgn>.
4908 Directly managing the /etc/rc?.d links and directly
4909 invoking the <file>/etc/init.d/</file> initscripts should
4910 be done only by packages providing the initscript
4911 subsystem (such as <prgn>sysvinit</prgn> and
4912 <prgn>file-rc</prgn>).
4917 <heading>Managing the links</heading>
4920 The program <prgn>update-rc.d</prgn> is provided for
4921 package maintainers to arrange for the proper creation and
4922 removal of <file>/etc/rc<var>n</var>.d</file> symbolic links,
4923 or their functional equivalent if another method is being
4924 used. This may be used by maintainers in their packages'
4925 <prgn>postinst</prgn> and <prgn>postrm</prgn> scripts.</p>
4928 You must not include any <file>/etc/rc<var>n</var>.d</file>
4929 symbolic links in the actual archive or manually create or
4930 remove the symbolic links in maintainer scripts; you must
4931 use the <prgn>update-rc.d</prgn> program instead. (The
4932 former will fail if an alternative method of maintaining
4933 runlevel information is being used.) You must not include
4934 the <file>/etc/rc<var>n</var>.d</file> directories themselves
4935 in the archive either. (Only the <tt>sysvinit</tt>
4940 By default <prgn>update-rc.d</prgn> will start services in
4941 each of the multi-user state runlevels (2, 3, 4, and 5)
4942 and stop them in the halt runlevel (0), the single-user
4943 runlevel (1) and the reboot runlevel (6). The system
4944 administrator will have the opportunity to customize
4945 runlevels by simply adding, moving, or removing the
4946 symbolic links in <file>/etc/rc<var>n</var>.d</file> if
4947 symbolic links are being used, or by modifying
4948 <file>/etc/runlevel.conf</file> if the <tt>file-rc</tt> method
4953 To get the default behavior for your package, put in your
4954 <prgn>postinst</prgn> script
4955 <example compact="compact">
4956 update-rc.d <var>package</var> defaults
4958 and in your <prgn>postrm</prgn>
4959 <example compact="compact">
4960 if [ "$1" = purge ]; then
4961 update-rc.d <var>package</var> remove
4963 </example>. Note that if your package changes runlevels
4964 or priority, you may have to remove and recreate the links,
4965 since otherwise the old links may persist. Refer to the
4966 documentation of <prgn>update-rc.d</prgn></p>
4969 This will use a default sequence number of 20. If it does
4970 not matter when or in which order the <file>init.d</file>
4971 script is run, use this default. If it does, then you
4972 should talk to the maintainer of the <prgn>sysvinit</prgn>
4973 package or post to <tt>debian-devel</tt>, and they will
4974 help you choose a number.
4978 For more information about using <tt>update-rc.d</tt>,
4979 please consult its manpage <manref name="update-rc.d"
4985 <heading>Running initscripts</heading>
4987 The program <prgn>invoke-rc.d</prgn> is provided to make
4988 it easier for package maintainers to properly invoke an
4989 initscript, obeying runlevel and other locally-defined
4990 constraints that might limit a package's right to start,
4991 stop and otherwise manage services. This program may be
4992 used by maintainers in their packages' scripts.
4995 The use of <prgn>invoke-rc.d</prgn> to invoke the
4996 <file>/etc/init.d/*</file> initscripts is strongly
4997 recommended<footnote>
4999 In the future, the use of invoke-rc.d to invoke
5000 initscripts shall be made mandatory. Maintainers are
5001 advised to switch to invoke-rc.d as soon as
5003 </footnote>, instead of calling them directly.
5007 By default, <prgn>invoke-rc.d</prgn> will pass any
5008 action requests (start, stop, reload, restart...) to the
5009 <file>/etc/init.d</file> script, filtering out requests
5010 to start or restart a service out of its intended
5014 Most packages will simply need to change:
5015 <example compact="compact">/etc/init.d/<package>
5016 <action></example> in their <prgn>postinst</prgn>
5017 and <prgn>prerm</prgn> scripts to:
5018 <example compact="compact">
5019 if [ -x /usr/sbin/invoke-rc.d ] ; then
5020 invoke-rc.d <var>package</var> <action>
5022 /etc/init.d/<var>package</var> <action>
5026 A package should register its initscript services using
5027 <prgn>update-rc.d</prgn> before it tries to invoke them
5028 using <prgn>invoke-rc.d</prgn>. Invocation of
5029 unregistered services may fail.
5032 For more information about using
5033 <prgn>invoke-rc.d</prgn>, please consult its manpage
5034 <manref name="invoke-rc.d" section="8">.
5041 <heading>Boot-time initialization</heading>
5044 There used to be another directory, <file>/etc/rc.boot</file>,
5045 which contained scripts which were run once per machine
5046 boot. This has been deprecated in favour of links from
5047 <file>/etc/rcS.d</file> to files in <file>/etc/init.d</file> as
5048 described in <ref id="/etc/init.d">. Packages must not
5049 place files in <file>/etc/rc.boot</file>.</p>
5052 <heading>Example</heading>
5055 The <prgn>bind</prgn> DNS (nameserver) package wants to
5056 make sure that the nameserver is running in multiuser
5057 runlevels, and is properly shut down with the system. It
5058 puts a script in <file>/etc/init.d</file>, naming the script
5059 appropriately <tt>bind</tt>. As you can see, the script
5060 interprets the argument <tt>reload</tt> to send the
5061 nameserver a <tt>HUP</tt> signal (causing it to reload its
5062 configuration); this way the system administrator can say
5063 <tt>/etc/init.d/bind reload</tt> to reload the name
5064 server. The script has one configurable value, which can
5065 be used to pass parameters to the named program at
5066 startup; this value is read from
5067 <file>/etc/default/bind</file> (see below).
5071 <example compact="compact">
5074 # Original version by Robert Leslie
5075 # <rob@mars.org>, edited by iwj and cs
5077 test -x /usr/sbin/named || exit 0
5079 # Source defaults file.
5081 if [ -f /etc/default/bind ]; then
5088 echo -n "Starting domain name service: named"
5089 start-stop-daemon --start --quiet --exec /usr/sbin/named \
5094 echo -n "Stopping domain name service: named"
5095 start-stop-daemon --stop --quiet \
5096 --pidfile /var/run/named.pid --exec /usr/sbin/named
5100 echo -n "Restarting domain name service: named"
5101 start-stop-daemon --stop --quiet \
5102 --pidfile /var/run/named.pid --exec /usr/sbin/named
5103 start-stop-daemon --start --verbose --exec /usr/sbin/named \
5107 force-reload|reload)
5108 echo -n "Reloading configuration of domain name service: named"
5109 start-stop-daemon --stop --signal 1 --quiet \
5110 --pidfile /var/run/named.pid --exec /usr/sbin/named
5114 echo "Usage: /etc/init.d/bind " \
5115 " {start|stop|restart|reload|force-reload}" >&2
5125 Complementing the above init script is a configuration
5126 file <file>/etc/default/bind</file>, which contains
5127 configurable parameters used by the script. This would be
5128 created by the <prgn>postinst</prgn> script if it was not
5129 already present, and removed on purge by the
5130 <prgn>postrm</prgn> script.
5131 <example compact="compact">
5132 # Specified parameters to pass to named. See named(8).
5133 # You may uncomment the following line, and edit to taste.
5139 Another example on which you can base your
5140 <file>/etc/init.d</file> scripts is found in
5141 <file>/etc/init.d/skeleton</file>.
5145 If this package is happy with the default setup from
5146 <prgn>update-rc.d</prgn>, namely an ordering number of 20
5147 and having named running in all runlevels, it can say in
5148 its <prgn>postinst</prgn>:
5149 <example compact="compact">
5150 update-rc.d bind defaults >/dev/null
5152 And in its <prgn>postrm</prgn>, to remove the links when the
5154 <example compact="compact">
5155 if [ "$1" = purge ]; then
5156 update-rc.d bind remove >/dev/null
5164 <heading>Console messages from <file>init.d</file> scripts</heading>
5167 This section describes the formats to be used for messages
5168 written to standard output by the <file>/etc/init.d</file>
5169 scripts. The intent is to improve the consistency of
5170 Debian's startup and shutdown look and feel. For this
5171 reason, please look very carefully at the details. We want
5172 the messages to have the same format in terms of wording,
5173 spaces, punctuation and case of letters.
5177 Here is a list of overall rules that you should use when you
5178 create output messages. They can be useful if you have a
5179 non-standard message that is not covered specifically in the
5187 Every message should fit in one line (fewer than 80
5188 characters), start with a capital letter and end with
5189 a period (<tt>.</tt>) and line feed (<tt>"\n"</tt>).
5195 If you want to express that the computer is working on
5196 something (that is, performing a specific task, not
5197 starting or stopping a program), we use an "ellipsis"
5198 (three dots: <tt>...</tt>). Note that we don't insert
5199 spaces before or after the dots. If the task has been
5200 completed we write <tt>done.</tt> and a line feed.
5206 Design your messages as if the computer is telling you
5207 what he is doing (let him be polite :-), but don't
5208 mention "him" directly. For example, if you think of
5210 <example compact="compact">
5211 I'm starting network daemons: nfsd mountd.
5214 <example compact="compact">
5215 Starting network daemons: nfsd mountd.
5223 There are standard message formats for the following
5224 situations. They should be used by the <tt>init.d</tt>
5231 <p>When daemons are started</p>
5234 If your script starts one or more daemons, the output
5235 should look like this (a single line, no leading
5237 <example compact="compact">
5238 Starting <var>description</var>: <var>daemon-1</var> ... <var>daemon-n</var>.
5240 The <var>description</var> should describe the
5241 subsystem the daemon or set of daemons are part of,
5242 while <var>daemon-1</var> up to <var>daemon-n</var>
5243 denote each daemon's name (typically the file name of
5248 For example, the output of <file>/etc/init.d/lpd</file>
5250 <example compact="compact">
5251 Starting printer spooler: lpd.
5256 This can be achieved by saying
5257 <example compact="compact">
5258 echo -n "Starting printer spooler: lpd"
5259 start-stop-daemon --start --quiet --exec /usr/sbin/lpd
5262 in the script. If you have more than one daemon to
5263 start, you should do the following:
5264 <example compact="compact">
5265 echo -n "Starting remote file system services:"
5266 echo -n " nfsd"; start-stop-daemon --start --quiet nfsd
5267 echo -n " mountd"; start-stop-daemon --start --quiet mountd
5268 echo -n " ugidd"; start-stop-daemon --start --quiet ugidd
5271 This makes it possible for the user to see what takes
5272 so long and when the final daemon has been started.
5273 You should be careful where to put spaces: in the
5274 example above the system administrator can easily
5275 comment out a line if he don't wants to start a
5276 specific daemon, while the displayed message still
5282 <p>When a system parameter is being set</p>
5285 If you have to set up different system parameters
5286 during the system boot, you should use this format:
5287 <example compact="compact">
5288 Setting <var>parameter</var> to "<var>value</var>".
5293 You can use a statement such as the following to get
5295 <example compact="compact">
5296 echo "Setting DNS domainname to \"$domainname\"."
5301 Note that the same symbol (<tt>"</tt>) is used for the left
5302 and right quotation marks. A grave accent (<tt>`</tt>) is
5303 not a quote character; neither is an apostrophe
5309 <p>When a daemon is stopped or restarted</p>
5312 When you stop or restart a daemon, you should issue a
5313 message identical to the startup message, except that
5314 <tt>Starting</tt> is replaced with <tt>Stopping</tt>
5315 or <tt>Restarting</tt> respectively.
5319 For example, stopping the printer daemon will like
5321 <example compact="compact">
5322 Stopping printer spooler: lpd.
5328 <p>When something is executed</p>
5331 There are several examples where you have to run a
5332 program at system startup or shutdown to perform a
5333 specific task, for example, setting the system's clock
5334 using <prgn>netdate</prgn> or killing all processes
5335 when the system shuts down. Your message should look
5337 <example compact="compact">
5338 Doing something very useful...done.
5340 You should print the <tt>done.</tt> immediately after
5341 the job has been completed, so that the user is
5342 informed why she has to wait. You can get this
5344 <example compact="compact">
5345 echo -n "Doing something very useful..."
5354 <p>When the configuration is reloaded</p>
5357 When a daemon is forced to reload its configuration
5358 files you should use the following format:
5359 <example compact="compact">
5360 Reloading <var>description</var> configuration...done.
5362 where <var>description</var> is the same as in the
5363 daemon starting message.
5371 <heading>Cron jobs</heading>
5374 Packages must not modify the configuration file
5375 <file>/etc/crontab</file>, and they must not modify the files in
5376 <file>/var/spool/cron/crontabs</file>.</p>
5379 If a package wants to install a job that has to be executed
5380 via cron, it should place a file with the name of the
5381 package in one or more of the following directories:
5382 <example compact="compact">
5387 As these directory names imply, the files within them are
5388 executed on a daily, weekly, or monthly basis,
5389 respectively. The exact times are listed in
5390 <file>/etc/crontab</file>.</p>
5393 All files installed in any of these directories must be
5394 scripts (e.g., shell scripts or Perl scripts) so that they
5395 can easily be modified by the local system administrator.
5396 In addition, they should be treated as configuration
5401 If a certain job has to be executed more frequently than
5402 daily, the package should install a file
5403 <file>/etc/cron.d/<var>package</var></file>. This file uses the
5404 same syntax as <file>/etc/crontab</file> and is processed by
5405 <prgn>cron</prgn> automatically. The file must also be
5406 treated as a configuration file. (Note that entries in the
5407 <file>/etc/cron.d</file> directory are not handled by
5408 <prgn>anacron</prgn>. Thus, you should only use this
5409 directory for jobs which may be skipped if the system is not
5413 The scripts or crontab entries in these directories should
5414 check if all necessary programs are installed before they
5415 try to execute them. Otherwise, problems will arise when a
5416 package was removed but not purged since configuration files
5417 are kept on the system in this situation.</p>
5421 <heading>Menus</heading>
5424 The Debian <tt>menu</tt> package provides a standard
5425 interface between packages providing applications and
5426 documents, and <em>menu programs</em> (either X window
5427 managers or text-based menu programs such as
5428 <prgn>pdmenu</prgn>).
5432 All packages that provide applications that need not be
5433 passed any special command line arguments for normal
5434 operation should register a menu entry for those
5435 applications, so that users of the <tt>menu</tt> package
5436 will automatically get menu entries in their window
5437 managers, as well in shells like <tt>pdmenu</tt>.
5441 Menu entries should follow the current menu policy.
5445 The menu policy can be found in the <tt>menu-policy</tt>
5446 files in the <tt>debian-policy</tt> package.
5447 They are also available from the Debian web mirrors at
5448 <tt><url name="/doc/packaging-manuals/menu-policy/"
5449 id="http://www.debian.org/doc/packaging-manuals/menu-policy/"></tt>
5450 and from the Debian archive mirrors at
5451 <tt><url name="/doc/package-developer/menu-policy.txt.gz"
5452 id="http://ftp.debian.org/debian/doc/package-developer/menu-policy.txt.gz"></tt>.
5456 Please also refer to the <em>Debian Menu System</em>
5457 documentation that comes with the <tt>menu</tt> package for
5458 information about how to register your applications and web
5464 <heading>Multimedia handlers</heading>
5467 MIME (Multipurpose Internet Mail Extensions, RFCs 2045-2049)
5468 is a mechanism for encoding files and data streams and
5469 providing meta-information about them, in particular their
5470 type (e.g. audio or video) and format (e.g. PNG, HTML,
5475 Registration of MIME type handlers allows programs like mail
5476 user agents and web browsers to to invoke these handlers to
5477 view, edit or display MIME types they don't support
5482 Packages which provide the ability to view/show/play,
5483 compose, edit or print MIME types should register themselves
5484 as such following the current MIME support policy.
5488 The MIME support policy can be found in the <tt>mime-policy</tt>
5489 files in the <tt>debian-policy</tt> package.
5490 They are also available from the Debian web mirrors at
5491 <tt><url name="/doc/packaging-manuals/mime-policy/"
5492 id="http://www.debian.org/doc/packaging-manuals/mime-policy/"></tt>
5493 and from the Debian archive mirrors at
5494 <tt><url name="/doc/package-developer/mime-policy.txt.gz"
5495 id="http://ftp.debian.org/debian/doc/package-developer/mime-policy.txt.gz"></tt>.
5501 <heading>Keyboard configuration</heading>
5504 To achieve a consistent keyboard configuration so that all
5505 applications interpret a keyboard event the same way, all
5506 programs in the Debian distribution must be configured to
5507 comply with the following guidelines.
5511 The following keys must have the specified interpretations:
5514 <tag><tt><--</tt></tag>
5515 <item><p>delete the character to the left of the cursor</p></item>
5517 <tag><tt>Delete</tt></tag>
5518 <item><p>delete the character to the right of the cursor</p></item>
5520 <tag><tt>Control+H</tt></tag>
5521 <item><p>emacs: the help prefix</p></item>
5524 The interpretation of any keyboard events should be
5525 independent of the terminal that is used, be it a virtual
5526 console, an X terminal emulator, an rlogin/telnet session,
5531 The following list explains how the different programs
5532 should be set up to achieve this:
5537 <item><p><tt><--</tt> generates <tt>KB_BackSpace</tt>
5540 <item><p><tt>Delete</tt> generates <tt>KB_Delete</tt> in
5545 X translations are set up to make
5546 <tt>KB_Backspace</tt> generate ASCII DEL, and to make
5547 <tt>KB_Delete</tt> generate <tt>ESC [ 3 ~</tt> (this
5548 is the vt220 escape code for the "delete character"
5549 key). This must be done by loading the X resources
5550 using <prgn>xrdb</prgn> on all local X displays, not
5551 using the application defaults, so that the
5552 translation resources used correspond to the
5553 <prgn>xmodmap</prgn> settings.</p></item>
5557 The Linux console is configured to make
5558 <tt><--</tt> generate DEL, and <tt>Delete</tt>
5559 generate <tt>ESC [ 3 ~</tt>.</p></item>
5563 X applications are configured so that <tt><</tt>
5564 deletes left, and <tt>Delete</tt> deletes right. Motif
5565 applications already work like this.</p></item>
5567 <item><p>Terminals should have <tt>stty erase ^?</tt> .</p></item>
5571 The <tt>xterm</tt> terminfo entry should have <tt>ESC
5572 [ 3 ~</tt> for <tt>kdch1</tt>, just as for
5573 <tt>TERM=linux</tt> and <tt>TERM=vt220</tt>.</p></item>
5577 Emacs is programmed to map <tt>KB_Backspace</tt> or
5578 the <tt>stty erase</tt> character to
5579 <tt>delete-backward-char</tt>, and <tt>KB_Delete</tt>
5580 or <tt>kdch1</tt> to <tt>delete-forward-char</tt>, and
5581 <tt>^H</tt> to <tt>help</tt> as always.</p></item>
5585 Other applications use the <tt>stty erase</tt>
5586 character and <tt>kdch1</tt> for the two delete keys,
5587 with ASCII DEL being "delete previous character" and
5588 <tt>kdch1</tt> being "delete character under
5595 This will solve the problem except for the following
5603 Some terminals have a <tt><--</tt> key that cannot
5604 be made to produce anything except <tt>^H</tt>. On
5605 these terminals Emacs help will be unavailable on
5606 <tt>^H</tt> (assuming that the <tt>stty erase</tt>
5607 character takes precedence in Emacs, and has been set
5608 correctly). <tt>M-x help</tt> or <tt>F1</tt> (if
5609 available) can be used instead.</p></item>
5613 Some operating systems use <tt>^H</tt> for <tt>stty
5614 erase</tt>. However, modern telnet versions and all
5615 rlogin versions propagate <tt>stty</tt> settings, and
5616 almost all UNIX versions honour <tt>stty erase</tt>.
5617 Where the <tt>stty</tt> settings are not propagated
5618 correctly, things can be made to work by using
5619 <tt>stty</tt> manually.</p></item>
5623 Some systems (including previous Debian versions) use
5624 <prgn>xmodmap</prgn> to arrange for both
5625 <tt><--</tt> and <tt>Delete</tt> to generate
5626 <tt>KB_Delete</tt>. We can change the behavior of
5627 their X clients using the same X resources that we use
5628 to do it for our own clients, or configure our clients
5629 using their resources when things are the other way
5630 around. On displays configured like this
5631 <tt>Delete</tt> will not work, but <tt><--</tt>
5636 Some operating systems have different <tt>kdch1</tt>
5637 settings in their <tt>terminfo</tt> database for
5638 <tt>xterm</tt> and others. On these systems the
5639 <tt>Delete</tt> key will not work correctly when you
5640 log in from a system conforming to our policy, but
5641 <tt><--</tt> will.</p></item>
5647 <heading>Environment variables</heading>
5650 A program must not depend on environment variables to get
5651 reasonable defaults. (That's because these environment
5652 variables would have to be set in a system-wide
5653 configuration file like <file>/etc/profile</file>, which is not
5654 supported by all shells.)</p>
5657 If a program usually depends on environment variables for its
5658 configuration, the program should be changed to fall back to
5659 a reasonable default configuration if these environment
5660 variables are not present. If this cannot be done easily
5661 (e.g., if the source code of a non-free program is not
5662 available), the program must be replaced by a small
5663 "wrapper" shell script which sets the environment variables
5664 if they are not already defined, and calls the original program.</p>
5667 Here is an example of a wrapper script for this purpose:
5669 <example compact="compact">
5671 BAR=${BAR:-/var/lib/fubar}
5673 exec /usr/lib/foo/foo "$@"
5678 Furthermore, as <file>/etc/profile</file> is a configuration
5679 file of the <prgn>base-files</prgn> package, other packages must not
5680 put any environment variables or other commands into that
5686 <heading>Files</heading>
5689 <heading>Binaries</heading>
5692 Two different packages must not install programs with
5693 different functionality but with the same filenames. (The
5694 case of two programs having the same functionality but
5695 different implementations is handled via "alternatives" or
5696 the "Conflicts" mechanism. See <ref id="maintscripts"> and
5697 <ref id="conflicts"> respectively.) If this case happens,
5698 one of the programs must be renamed. The maintainers should
5699 report this to the <tt>debian-devel</tt> mailing list and
5700 try to find a consensus about which program will have to be
5701 renamed. If a consensus cannot be reached, <em>both</em>
5702 programs must be renamed.
5706 By default, when a package is being built, any binaries
5707 created should include debugging information, as well as
5708 being compiled with optimization. You should also turn on
5709 as many reasonable compilation warnings as possible; this
5710 makes life easier for porters, who can then look at build
5711 logs for possible problems. For the C programming language,
5712 this means the following compilation parameters should be
5714 <example compact="compact">
5716 CFLAGS = -O2 -g -Wall # sane warning options vary between programs
5718 install -s # (or use strip on the files in debian/tmp)
5723 Note that by default all installed binaries should be stripped,
5724 either by using the <tt>-s</tt> flag to
5725 <prgn>install</prgn>, or by calling <prgn>strip</prgn> on
5726 the binaries after they have been copied into
5727 <file>debian/tmp</file> but before the tree is made into a
5731 Although binaries in the build tree should be compiled with
5732 debugging information by default, it can often be difficult
5733 to debug programs if they are also subjected to compiler
5734 optimization. For this reason, it is recommended to support
5735 the standardized environment
5736 variable <tt>DEB_BUILD_OPTIONS</tt>. This variable can
5737 contain several flags to change how a package is compiled
5745 The presence of this string means that the package
5746 should be complied with a minimum of optimization.
5747 For C programs, it is best to add <tt>-O0</tt>
5748 to <tt>CFLAGS</tt> (although this is usually the
5749 default). Some programs might fail to build or run at
5750 this level of optimization; it may be necessary to
5751 use <tt>-O1</tt>, for example.
5757 This string means that the debugging symbols should
5758 not be stripped from the binary during installation,
5759 so that debugging information may be included in the package.
5765 The following makefile snippet is an example of how one may
5766 implement the build options; you will probably have to
5767 massage this example in order to make it work for your
5769 <example compact="compact">
5772 INSTALL_FILE = $(INSTALL) -p -o root -g root -m 644
5773 INSTALL_PROGRAM = $(INSTALL) -p -o root -g root -m 755
5774 INSTALL_SCRIPT = $(INSTALL) -p -o root -g root -m 755
5775 INSTALL_DIR = $(INSTALL) -p -d -o root -g root -m 755
5777 ifneq (,$(findstring noopt,$(DEB_BUILD_OPTIONS)))
5782 ifeq (,$(findstring nostrip,$(DEB_BUILD_OPTIONS)))
5783 INSTALL_PROGRAM += -s
5789 It is up to the package maintainer to decide what
5790 compilation options are best for the package. Certain
5791 binaries (such as computationally-intensive programs) will
5792 function better with certain flags (<tt>-O3</tt>, for
5793 example); feel free to use them. Please use good judgment
5794 here. Don't use flags for the sake of it; only use them
5795 if there is good reason to do so. Feel free to override
5796 the upstream author's ideas about which compilation
5797 options are best: they are often inappropriate for our
5803 <sect id="libraries">
5804 <heading>Libraries</heading>
5807 The shared version of a library must be compiled with
5808 <tt>-fPIC</tt>, and the static version must not be. In other
5809 words, each source unit (<tt>*.c</tt>, for example, for C files)
5810 will need to be compiled twice.
5815 You must specify the gcc option <tt>-D_REENTRANT</tt>
5816 when building a library (either static or shared) to make
5817 the library compatible with LinuxThreads.
5821 All installed shared libraries should be stripped with
5822 <example compact="compact">
5823 strip --strip-unneeded <var>your-lib</var>
5825 (The option <tt>--strip-unneeded</tt> makes
5826 <prgn>strip</prgn> remove only the symbols which aren't
5827 needed for relocation processing.) Shared libraries can
5828 function perfectly well when stripped, since the symbols for
5829 dynamic linking are in a separate part of the ELF object
5832 You might also want to use the options
5833 <tt>--remove-section=.comment</tt> and
5834 <tt>--remove-section=.note</tt> on both shared libraries
5835 and executables, and <tt>--strip-debug</tt> on static
5842 Note that under some circumstances it may be useful to
5843 install a shared library unstripped, for example when
5844 building a separate package to support debugging.
5848 Shared object files (often <file>.so</file> files) that are not
5849 public libraries, that is, they are not meant to be linked
5850 to by third party executables (binaries of other packages),
5851 should be installed in subdirectories of the
5852 <file>/usr/lib</file> directory. Such files are exempt from the
5853 rules that govern ordinary shared libraries, except that
5854 they must not be installed executable and should be
5857 A common example are the so-called "plug-ins",
5858 internal shared objects that are dynamically loaded by
5859 programs using <manref name="dlopen" section="3">.
5865 Packages containing shared libraries that may be linked to
5866 by other packages' binaries, but which for some
5867 <em>compelling</em> reason can not be installed in
5868 <file>/usr/lib</file> directory, may install the shared library
5869 files in subdirectories of the <file>/usr/lib</file> directory,
5870 in which case they should arrange to add that directory in
5871 <file>/etc/ld.so.conf</file> in the package's post-installation
5872 script, and remove it in the package's post-removal script.
5876 An ever increasing number of packages are using
5877 <prgn>libtool</prgn> to do their linking. The latest GNU
5878 libtools (>= 1.3a) can take advantage of the metadata in the
5879 installed <prgn>libtool</prgn> archive files (<file>*.la</file>
5880 files). The main advantage of <prgn>libtool</prgn>'s
5881 <file>.la</file> files is that it allows <prgn>libtool</prgn> to
5882 store and subsequently access metadata with respect to the
5883 libraries it builds. <prgn>libtool</prgn> will search for
5884 those files, which contain a lot of useful information about
5885 a library (such as library dependency information for static
5886 linking). Also, they're <em>essential</em> for programs
5887 using <tt>libltdl</tt>.<footnote>
5889 Although <prgn>libtool</prgn> is fully capable of
5890 linking against shared libraries which don't have
5891 <tt>.la</tt> files, as it is a mere shell script it can
5892 add considerably to the build time of a
5893 <prgn>libtool</prgn>-using package if that shell script
5894 has to derive all this information from first principles
5895 for each library every time it is linked. With the
5896 advent of <prgn>libtool</prgn> version 1.4 (and to a
5897 lesser extent <prgn>libtool</prgn> version 1.3), the
5898 <file>.la</file> files also store information about
5899 inter-library dependencies which cannot necessarily be
5900 derived after the <file>.la</file> file is deleted.
5906 Packages that use <prgn>libtool</prgn> to create shared
5907 libraries should include the <file>.la</file> files in the
5908 <tt>-dev</tt> package, unless the package relies on
5909 <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
5910 the <tt>.la</tt> files must go in the run-time library
5915 You must make sure that you use only released versions of
5916 shared libraries to build your packages; otherwise other
5917 users will not be able to run your binaries
5918 properly. Producing source packages that depend on
5919 unreleased compilers is also usually a bad
5926 <heading>Shared libraries</heading>
5928 This section has moved to <ref id="sharedlibs">.
5934 <heading>Scripts</heading>
5937 All command scripts, including the package maintainer
5938 scripts inside the package and used by <prgn>dpkg</prgn>,
5939 should have a <tt>#!</tt> line naming the shell to be used
5940 to interpret them.</p>
5943 In the case of Perl scripts this should be
5944 <tt>#!/usr/bin/perl</tt>.</p>
5947 Shell scripts (<prgn>sh</prgn> and <prgn>bash</prgn>)
5948 should almost certainly start with <tt>set -e</tt> so that
5949 errors are detected. Every script should use
5950 <tt>set -e</tt> or check the exit status of <em>every</em>
5954 The standard shell interpreter <file>/bin/sh</file> can be a
5955 symbolic link to any POSIX compatible shell, if <tt>echo
5956 -n</tt> does not generate a newline.<footnote>
5958 Debian policy specifies POSIX behavior for
5959 <file>/bin/sh</file>, but <tt>echo -n</tt> has widespread
5960 use in the Linux community (in particular including this
5961 policy, the Linux kernel source, many Debian scripts,
5962 etc.). This <tt>echo -n</tt> mechanism is valid but not
5963 required under POSIX, hence this explicit addition.
5964 Also, rumour has it that this shall be mandated under
5968 Thus, shell scripts specifying <file>/bin/sh</file> as
5969 interpreter should only use POSIX features. If a script
5970 requires non-POSIX features from the shell interpreter, the
5971 appropriate shell must be specified in the first line of the
5972 script (e.g., <tt>#!/bin/bash</tt>) and the package must
5973 depend on the package providing the shell (unless the shell
5974 package is marked "Essential", as in the case of
5979 You may wish to restrict your script to POSIX features when
5980 possible so that it may use <file>/bin/sh</file> as its
5981 interpreter. If your script works with <prgn>dash</prgn>
5982 (originally called <prgn>ash</prgn>), it's probably POSIX
5983 compliant, but if you are in doubt, use
5984 <file>/bin/bash</file>.
5988 Perl scripts should check for errors when making any
5989 system calls, including <tt>open</tt>, <tt>print</tt>,
5990 <tt>close</tt>, <tt>rename</tt> and <tt>system</tt>.
5994 <prgn>csh</prgn> and <prgn>tcsh</prgn> should be avoided as
5995 scripting languages. See <em>Csh Programming Considered
5996 Harmful</em>, one of the <tt>comp.unix.*</tt> FAQs, which
5997 can be found at <url
5998 id="http://language.perl.com/versus/csh.whynot">.<footnote>
6000 It can also be found on
6001 <url id="http://www.cpan.org/doc/FMTEYEWTK/versus/csh.whynot">
6002 or on the ftp site <ftpsite>ftp.cpan.org</ftpsite> as
6003 <ftppath>/pub/perl/CPAN/doc/FMTEYEWTK/versus/csh.whynot</ftppath>.
6006 If an upstream package comes with <prgn>csh</prgn> scripts
6007 then you must make sure that they start with
6008 <tt>#!/bin/csh</tt> and make your package depend on the
6009 <prgn>c-shell</prgn> virtual package.
6013 Any scripts which create files in world-writeable
6014 directories (e.g., in <file>/tmp</file>) must use a
6015 mechanism which will fail if a file with the same name
6019 The Debian base system provides the <prgn>tempfile</prgn>
6020 and <prgn>mktemp</prgn> utilities for use by scripts for
6021 this purpose.</p></sect>
6025 <heading>Symbolic links</heading>
6028 In general, symbolic links within a top-level directory
6029 should be relative, and symbolic links pointing from one
6030 top-level directory into another should be absolute. (A
6031 top-level directory is a sub-directory of the root
6032 directory <file>/</file>.)</p>
6035 In addition, symbolic links should be specified as short as
6036 possible, i.e., link targets like <file>foo/../bar</file> are
6040 Note that when creating a relative link using
6041 <prgn>ln</prgn> it is not necessary for the target of the
6042 link to exist relative to the working directory you're
6043 running <prgn>ln</prgn> from, nor is it necessary to change
6044 directory to the directory where the link is to be made.
6045 Simply include the string that should appear as the target
6046 of the link (this will be a pathname relative to the
6047 directory in which the link resides) as the first argument
6048 to <prgn>ln</prgn>.</p>
6051 For example, in your <prgn>Makefile</prgn> or
6052 <file>debian/rules</file>, you can do things like:
6053 <example compact="compact">
6054 ln -fs gcc $(prefix)/bin/cc
6055 ln -fs gcc debian/tmp/usr/bin/cc
6056 ln -fs ../sbin/sendmail $(prefix)/bin/runq
6057 ln -fs ../sbin/sendmail debian/tmp/usr/bin/runq
6061 A symbolic link pointing to a compressed file should always
6062 have the same file extension as the referenced file. (For
6063 example, if a file <file>foo.gz</file> is referenced by a
6064 symbolic link, the filename of the link has to end with
6065 "<file>.gz</file>" too, as in <file>bar.gz</file>.)
6070 <heading>Device files</heading>
6073 Packages must not include device files in the package file
6077 If a package needs any special device files that are not
6078 included in the base system, it must call
6079 <prgn>MAKEDEV</prgn> in the <prgn>postinst</prgn> script,
6080 after notifying the user<footnote>
6082 This notification could be done via a (low-priority)
6083 debconf message, or an echo (printf) statement.
6089 Packages must not remove any device files in the
6090 <prgn>postrm</prgn> or any other script. This is left to the
6091 system administrator.</p>
6094 Debian uses the serial devices
6095 <file>/dev/ttyS*</file>. Programs using the old
6096 <file>/dev/cu*</file> devices should be changed to use
6097 <file>/dev/ttyS*</file>.</p>
6100 <sect id="config-files">
6101 <heading>Configuration files</heading>
6103 <heading>Definitions</heading>
6106 <tag>configuration file</tag>
6109 A file that affects the operation of a program, or
6110 provides site- or host-specific information, or
6111 otherwise customizes the behavior of a program.
6112 Typically, configuration files are intended to be
6113 modified by the system administrator (if needed or
6114 desired) to conform to local policy or to provide
6115 more useful site-specific behavior.
6119 <tag><tt>conffile</tt></tag>
6122 A file listed in a package's <tt>conffiles</tt>
6123 file, and is treated specially by <prgn>dpkg</prgn>
6124 (see <ref id="configdetails">).
6131 The distinction between these two is important; they are
6132 not interchangeable concepts. Almost all
6133 <tt>conffile</tt>s are configuration files, but many
6134 configuration files are not <tt>conffiles</tt>.
6138 Note that a script that embeds configuration information
6139 (such as most of the files in <file>/etc/default</file> and
6140 <file>/etc/cron.{daily,weekly,monthly}</file>) is de-facto a
6141 configuration file and should be treated as such.
6146 <heading>Location</heading>
6148 Any configuration files created or used by your package
6149 must reside in <file>/etc</file>. If there are several,
6150 consider creating a subdirectory of <file>/etc</file>
6151 named after your package.</p>
6154 If your package creates or uses configuration files
6155 outside of <file>/etc</file>, and it is not feasible to modify
6156 the package to use <file>/etc</file> directly, put the files
6157 in <file>/etc</file> and create symbolic links to those files
6158 from the location that the package requires.</p>
6162 <heading>Behavior</heading>
6164 Configuration file handling must conform to the following
6166 <list compact="compact">
6169 local changes must be preserved during a package
6175 configuration files must be preserved when the
6176 package is removed, and only deleted when the
6184 The easy way to achieve this behavior is to make the
6185 configuration file a <tt>conffile</tt>. This is
6186 appropriate only if it is possible to distribute a default
6187 version that will work for most installations, although
6188 some system administrators may choose to modify it. This
6189 implies that the default version will be part of the
6190 package distribution, and must not be modified by the
6191 maintainer scripts during installation (or at any other
6196 In order to ensure that local changes are preserved
6197 correctly, no package may contain or make hard links to
6198 conffiles.<footnote>
6200 Rationale: There are two problems with hard links.
6201 The first is that some editors break the link while
6202 editing one of the files, so that the two files may
6203 unwittingly become unlinked and different. The second
6204 is that <prgn>dpkg</prgn> might break the hard link
6205 while upgrading <tt>conffile</tt>s.
6211 The other way to do it is via the maintainer scripts. In
6212 this case, the configuration file must not be listed as a
6213 <tt>conffile</tt> and must not be part of the package
6214 distribution. If the existence of a file is required for
6215 the package to be sensibly configured it is the
6216 responsibility of the package maintainer to provide
6217 maintainer scripts which correctly create, update and
6218 maintain the file and remove it on purge. (See <ref
6219 id="maintainerscripts"> for more information.) These
6220 scripts must be idempotent (i.e., must work correctly if
6221 <prgn>dpkg</prgn> needs to re-run them due to errors
6222 during installation or removal), must cope with all the
6223 variety of ways <prgn>dpkg</prgn> can call maintainer
6224 scripts, must not overwrite or otherwise mangle the user's
6225 configuration without asking, must not ask unnecessary
6226 questions (particularly during upgrades), and otherwise be
6231 The scripts are not required to configure every possible
6232 option for the package, but only those necessary to get
6233 the package running on a given system. Ideally the
6234 sysadmin should not have to do any configuration other
6235 than that done (semi-)automatically by the
6236 <prgn>postinst</prgn> script.
6240 A common practice is to create a script called
6241 <file><var>package</var>-configure</file> and have the
6242 package's <prgn>postinst</prgn> call it if and only if the
6243 configuration file does not already exist. In certain
6244 cases it is useful for there to be an example or template
6245 file which the maintainer scripts use. Such files should
6246 be in <file>/usr/share/<var>package</var></file> or
6247 <file>/usr/lib/<var>package</var></file> (depending on whether
6248 they are architecture-independent or not). There should
6249 be symbolic links to them from
6250 <file>/usr/share/doc/<var>package</var>/examples</file> if
6251 they are examples, and should be perfectly ordinary
6252 <prgn>dpkg</prgn>-handled files (<em>not</em>
6253 configuration files).
6257 These two styles of configuration file handling must
6258 not be mixed, for that way lies madness:
6259 <prgn>dpkg</prgn> will ask about overwriting the file
6260 every time the package is upgraded.
6265 <heading>Sharing configuration files</heading>
6267 Packages which specify the same file as a
6268 <tt>conffile</tt> must be tagged as <em>conflicting</em>
6269 with each other. (This is an instance of the general rule
6270 about not sharing files. Note that neither alternatives
6271 nor diversions are likely to be appropriate in this case;
6272 in particular, <prgn>dpkg</prgn> does not handle diverted
6273 <tt>conffile</tt>s well.)
6277 The maintainer scripts must not alter a <tt>conffile</tt>
6278 of <em>any</em> package, including the one the scripts
6283 If two or more packages use the same configuration file
6284 and it is reasonable for both to be installed at the same
6285 time, one of these packages must be defined as
6286 <em>owner</em> of the configuration file, i.e., it will be
6287 the package which handles that file as a configuration
6288 file. Other packages that use the configuration file must
6289 depend on the owning package if they require the
6290 configuration file to operate. If the other package will
6291 use the configuration file if present, but is capable of
6292 operating without it, no dependency need be declared.</p>
6295 If it is desirable for two or more related packages to
6296 share a configuration file <em>and</em> for all of the
6297 related packages to be able to modify that configuration
6298 file, then the following should be done:
6299 <enumlist compact="compact">
6302 One of the related packages (the "owning" package)
6303 will manage the configuration file with maintainer
6304 scripts as described in the previous section.
6309 The owning package should also provide a program
6310 that the other packages may use to modify the
6316 The related packages must use the provided program
6317 to make any desired modifications to the
6318 configuration file. They should either depend on
6319 the core package to guarantee that the configuration
6320 modifier program is available or accept gracefully
6321 that they cannot modify the configuration file if it
6322 is not. (This is in addition to the fact that the
6323 configuration file may not even be present in the
6331 Sometimes it's appropriate to create a new package which
6332 provides the basic infrastructure for the other packages
6333 and which manages the shared configuration files. (The
6334 <tt>sgml-base</tt> package is a good example.)
6339 <heading>User configuration files ("dotfiles")</heading>
6342 The files in <file>/etc/skel</file> will automatically be
6343 copied into new user accounts by <prgn>adduser</prgn>.
6344 No other program should reference the files in
6345 <file>/etc/skel</file>.
6349 Therefore, if a program needs a dotfile to exist in
6350 advance in <file>$HOME</file> to work sensibly, that dotfile
6351 should be installed in <file>/etc/skel</file> and treated as a
6356 However, programs that require dotfiles in order to
6357 operate sensibly are a bad thing, unless they do create
6358 the dotfiles themselves automatically.
6362 Furthermore, programs should be configured by the Debian
6363 default installation to behave as closely to the upstream
6364 default behaviour as possible.
6368 Therefore, if a program in a Debian package needs to be
6369 configured in some way in order to operate sensibly, that
6370 should be done using a site-wide configuration file placed
6371 in <file>/etc</file>. Only if the program doesn't support a
6372 site-wide default configuration and the package maintainer
6373 doesn't have time to add it may a default per-user file be
6374 placed in <file>/etc/skel</file>.
6378 <file>/etc/skel</file> should be as empty as we can make it.
6379 This is particularly true because there is no easy (or
6380 necessarily desirable) mechanism for ensuring that the
6381 appropriate dotfiles are copied into the accounts of
6382 existing users when a package is installed.
6388 <heading>Log files</heading>
6390 Log files should usually be named
6391 <file>/var/log/<var>package</var>.log</file>. If you have many
6392 log files, or need a separate directory for permission
6393 reasons (<file>/var/log</file> is writable only by
6394 <file>root</file>), you should usually create a directory named
6395 <file>/var/log/<var>package</var></file> and place your log
6400 Log files must be rotated occasionally so that they don't
6401 grow indefinitely; the best way to do this is to drop a log
6402 rotation configuration file into the directory
6403 <file>/etc/logrotate.d</file> and use the facilities provided by
6404 logrotate.<footnote>
6406 The traditional approach to log files has been to set up
6407 <em>ad hoc</em> log rotation schemes using simple shell
6408 scripts and cron. While this approach is highly
6409 customizable, it requires quite a lot of sysadmin work.
6410 Even though the original Debian system helped a little
6411 by automatically installing a system which can be used
6412 as a template, this was deemed not enough.
6416 The use of <prgn>logrotate</prgn>, a program developed
6417 by Red Hat, is better, as it centralizes log management.
6418 It has both a configuration file
6419 (<file>/etc/logrotate.conf</file>) and a directory where
6420 packages can drop their individual log rotation
6421 configurations (<file>/etc/logrotate.d</file>).
6424 Here is a good example for a logrotate config
6425 file (for more information see <manref name="logrotate"
6427 <example compact="compact">
6428 /var/log/foo/*.log {
6433 /etc/init.d/foo force-reload
6437 This rotates all files under <file>/var/log/foo</file>, saves 12
6438 compressed generations, and forces the daemon to reload its
6439 configuration information after the log rotation.
6443 Log files should be removed when the package is
6444 purged (but not when it is only removed). This should be
6445 done by the <prgn>postrm</prgn> script when it is called
6446 with the argument <tt>purge</tt> (see <ref
6447 id="removedetails">).
6452 <heading>Permissions and owners</heading>
6455 The rules in this section are guidelines for general use.
6456 If necessary you may deviate from the details below.
6457 However, if you do so you must make sure that what is done
6458 is secure and you should try to be as consistent as possible
6459 with the rest of the system. You should probably also
6460 discuss it on <prgn>debian-devel</prgn> first.
6464 Files should be owned by <tt>root.root</tt>, and made
6465 writable only by the owner and universally readable (and
6466 executable, if appropriate), that is mode 644 or 755.
6470 Directories should be mode 755 or (for group-writability)
6471 mode 2775. The ownership of the directory should be
6472 consistent with its mode: if a directory is mode 2775, it
6473 should be owned by the group that needs write access to
6478 Setuid and setgid executables should be mode 4755 or 2755
6479 respectively, and owned by the appropriate user or group.
6480 They should not be made unreadable (modes like 4711 or
6481 2711 or even 4111); doing so achieves no extra security,
6482 because anyone can find the binary in the freely available
6483 Debian package; it is merely inconvenient. For the same
6484 reason you should not restrict read or execute permissions
6485 on non-set-id executables.
6489 Some setuid programs need to be restricted to particular
6490 sets of users, using file permissions. In this case they
6491 should be owned by the uid to which they are set-id, and by
6492 the group which should be allowed to execute them. They
6493 should have mode 4754; again there is no point in making
6494 them unreadable to those users who must not be allowed to
6499 It is possible to arrange that the system administrator can
6500 reconfigure the package to correspond to their local
6501 security policy by changing the permissions on a binary:
6502 they can do this by using <prgn>dpkg-statoverride</prgn>, as
6503 described below.<footnote>
6505 Ordinary files installed by <prgn>dpkg</prgn> (as
6506 opposed to <tt>conffile</tt>s and other similar objects)
6507 normally have their permissions reset to the distributed
6508 permissions when the package is reinstalled. However,
6509 the use of <prgn>dpkg-statoverride</prgn> overrides this
6510 default behaviour. If you use this method, you should
6511 remember to describe <prgn>dpkg-statoverride</prgn> in
6512 the package documentation; being a relatively new
6513 addition to Debian, it is probably not yet well-known.
6516 Another method you should consider is to create a group for
6517 people allowed to use the program(s) and make any setuid
6518 executables executable only by that group.
6522 If you need to create a new user or group for your package
6523 there are two possibilities. Firstly, you may need to
6524 make some files in the binary package be owned by this
6525 user or group, or you may need to compile the user or
6526 group id (rather than just the name) into the binary
6527 (though this latter should be avoided if possible, as in
6528 this case you need a statically allocated id).</p>
6531 If you need a statically allocated id, you must ask for a
6532 user or group id from the <tt>base-passwd</tt> maintainer,
6533 and must not release the package until you have been
6534 allocated one. Once you have been allocated one you must
6535 either make the package depend on a version of the
6536 <tt>base-passwd</tt> package with the id present in
6537 <file>/etc/passwd</file> or <file>/etc/group</file>, or arrange for
6538 your package to create the user or group itself with the
6539 correct id (using <tt>adduser</tt>) in its
6540 <prgn>preinst</prgn> or <prgn>postinst</prgn>. (Doing it in
6541 the <prgn>postinst</prgn> is to be preferred if it is
6542 possible, otherwise a pre-dependency will be needed on the
6543 <tt>adduser</tt> package.)
6547 On the other hand, the program might be able to determine
6548 the uid or gid from the user or group name at runtime, so
6549 that a dynamically allocated id can be used. In this case
6550 you should choose an appropriate user or group name,
6551 discussing this on <prgn>debian-devel</prgn> and checking
6552 with the <package/base-passwd/ maintainer that it is unique and that
6553 they do not wish you to use a statically allocated id
6554 instead. When this has been checked you must arrange for
6555 your package to create the user or group if necessary using
6556 <prgn>adduser</prgn> in the <prgn>preinst</prgn> or
6557 <prgn>postinst</prgn> script (again, the latter is to be
6558 preferred if it is possible).
6562 Note that changing the numeric value of an id associated
6563 with a name is very difficult, and involves searching the
6564 file system for all appropriate files. You need to think
6565 carefully whether a static or dynamic id is required, since
6566 changing your mind later will cause problems.
6569 <sect1><heading>The use of <prgn>dpkg-statoverride</prgn></heading>
6571 This section is not intended as policy, but as a
6572 description of the use of <prgn>dpkg-statoverride</prgn>.
6576 <prgn>dpkg-statoverride</prgn> is a replacement for the
6577 deprecated <tt>suidmanager</tt> package. Packages which
6578 previously used <tt>suidmanager</tt> should have a
6579 <tt>Conflicts: suidmanager (<< 0.50)</tt> entry (or even
6580 <tt>(<< 0.52)</tt>), and calls to <tt>suidregister</tt>
6581 and <tt>suidunregister</tt> should now be simply removed
6582 from the maintainer scripts.
6586 If a system administrator wishes to have a file (or
6587 directory or other such thing) installed with owner and
6588 permissions different from those in the distributed Debian
6589 package, he can use the <prgn>dpkg-statoverride</prgn>
6590 program to instruct <prgn>dpkg</prgn> to use the different
6591 settings every time the file is installed. Thus the
6592 package maintainer should distribute the files with their
6593 normal permissions, and leave it for the system
6594 administrator to make any desired changes. For example, a
6595 daemon which is normally required to be setuid root, but
6596 in certain situations could be used without being setuid,
6597 should be installed setuid in the <tt>.deb</tt>. Then the
6598 local system administrator can change this if they wish.
6599 If there are two standard ways of doing it, the package
6600 maintainer can use <tt>debconf</tt> to find out the
6601 preference, and call <prgn>dpkg-statoverride</prgn> in the
6602 maintainer script if necessary to accommodate the system
6603 administrator's choice.
6607 Given the above, <prgn>dpkg-statoverride</prgn> is
6608 essentially a tool for system administrators and would not
6609 normally be needed in the maintainer scripts. There is
6610 one type of situation, though, where calls to
6611 <prgn>dpkg-statoverride</prgn> would be needed in the
6612 maintainer scripts, and that involves packages which use
6613 dynamically allocated user or group ids. In such a
6614 situation, something like the following idiom can be very
6615 helpful in the package's <prgn>postinst</prgn>, where
6616 <tt>sysuser</tt> is a dynamically allocated id:
6618 for i in /usr/bin/foo /usr/sbin/bar
6620 if ! dpkg-statoverride --list $i >/dev/null
6622 dpkg-statoverride --update --add sysuser root 4755 $i
6626 The corresponding <tt>dpkg-statoverride --remove</tt>
6627 calls can then be made unconditionally when the package is
6634 <chapt id="customized-programs">
6635 <heading>Customized programs</heading>
6637 <sect id="arch-spec">
6638 <heading>Architecture specification strings</heading>
6641 If a program needs to specify an <em>architecture specification
6642 string</em> in some place, the following format should be
6643 used: <var>arch</var>-<var>os</var><footnote>
6645 The following architectures and operating systems are
6646 currently recognised by <prgn>dpkg-archictecture</prgn>.
6647 The architecture, <tt><var>arch</var></tt>, is one of
6648 the following: <tt>alpha</tt>, <tt>arm</tt>,
6649 <tt>hppa</tt>, <tt>i386</tt>, <tt>ia64</tt>,
6650 <tt>m68k</tt>, <tt>mips</tt>, <tt>mipsel</tt>,
6651 <tt>powerpc</tt>, <tt>s390</tt>, <tt>sh</tt>,
6652 <tt>sheb</tt>, <tt>sparc</tt> and <tt>sparc64</tt>. The
6653 operating system, <tt><var>os</var></tt>, is one of:
6654 <tt>linux</tt>, <tt>gnu</tt>, <tt>freebsd</tt> and
6655 <tt>openbsd</tt>. Use of <tt>gnu</tt> in this string is
6656 reserved for the GNU/Hurd operating system.
6662 Note that we don't want to use
6663 <tt><var>arch</var>-debian-linux</tt> to apply to the rule
6664 <tt><var>architecture</var>-<var>vendor</var>-<var>os</var></tt>
6665 since this would make our programs incompatible with other
6666 Linux distributions. We also don't use something like
6667 <tt><var>arch</var>-unknown-linux</tt>, since the
6668 <tt>unknown</tt> does not look very good.
6673 <heading>Daemons</heading>
6676 The configuration files <file>/etc/services</file>,
6677 <file>/etc/protocols</file>, and <file>/etc/rpc</file> are managed
6678 by the <prgn>netbase</prgn> package and must not be modified
6683 If a package requires a new entry in one of these files, the
6684 maintainer should get in contact with the
6685 <prgn>netbase</prgn> maintainer, who will add the entries
6686 and release a new version of the <prgn>netbase</prgn>
6691 The configuration file <file>/etc/inetd.conf</file> must not be
6692 modified by the package's scripts except via the
6693 <prgn>update-inetd</prgn> script or the
6694 <file>DebianNet.pm</file> Perl module. See their documentation
6695 for details on how to add entries.
6699 If a package wants to install an example entry into
6700 <file>/etc/inetd.conf</file>, the entry must be preceded with
6701 exactly one hash character (<tt>#</tt>). Such lines are
6702 treated as "commented out by user" by the
6703 <prgn>update-inetd</prgn> script and are not changed or
6704 activated during package updates.
6709 <heading>Using pseudo-ttys and modifying wtmp, utmp and
6713 Some programs need to create pseudo-ttys. This should be done
6714 using Unix98 ptys if the C library supports it. The resulting
6715 program must not be installed setuid root, unless that
6716 is required for other functionality.
6720 The files <file>/var/run/utmp</file>, <file>/var/log/wtmp</file> and
6721 <file>/var/log/lastlog</file> must be installed writeable by
6722 group <tt>utmp</tt>. Programs which need to modify those
6723 files must be installed setgid <tt>utmp</tt>.
6728 <heading>Editors and pagers</heading>
6731 Some programs have the ability to launch an editor or pager
6732 program to edit or display a text document. Since there are
6733 lots of different editors and pagers available in the Debian
6734 distribution, the system administrator and each user should
6735 have the possibility to choose his/her preferred editor and
6740 In addition, every program should choose a good default
6741 editor/pager if none is selected by the user or system
6746 Thus, every program that launches an editor or pager must
6747 use the EDITOR or PAGER environment variable to determine
6748 the editor or pager the user wishes to use. If these
6749 variables are not set, the programs <file>/usr/bin/editor</file>
6750 and <file>/usr/bin/pager</file> should be used, respectively.
6754 These two files are managed through the <prgn>dpkg</prgn>
6755 "alternatives" mechanism. Thus every package providing an
6756 editor or pager must call the
6757 <prgn>update-alternatives</prgn> script to register these
6762 If it is very hard to adapt a program to make use of the
6763 EDITOR or PAGER variables, that program may be configured to
6764 use <file>/usr/bin/sensible-editor</file> and
6765 <file>/usr/bin/sensible-pager</file> as the editor or pager
6766 program respectively. These are two scripts provided in the
6767 Debian base system that check the EDITOR and PAGER variables
6768 and launch the appropriate program, and fall back to
6769 <file>/usr/bin/editor</file> and <file>/usr/bin/pager</file> if the
6770 variable is not set.
6774 A program may also use the VISUAL environment variable to
6775 determine the user's choice of editor. If it exists, it
6776 should take precedence over EDITOR. This is in fact what
6777 <file>/usr/bin/sensible-editor</file> does.
6781 It is not required for a package to depend on
6782 <tt>editor</tt> and <tt>pager</tt>, nor is it required for a
6783 package to provide such virtual packages.<footnote>
6785 The Debian base system already provides an editor and a
6792 <sect id="web-appl">
6793 <heading>Web servers and applications</heading>
6796 This section describes the locations and URLs that should
6797 be used by all web servers and web applications in the
6805 Cgi-bin executable files are installed in the
6807 <example compact="compact">
6808 /usr/lib/cgi-bin/<var>cgi-bin-name</var>
6810 and should be referred to as
6811 <example compact="compact">
6812 http://localhost/cgi-bin/<var>cgi-bin-name</var>
6817 <item><p>Access to HTML documents</p>
6820 HTML documents for a package are stored in
6821 <file>/usr/share/doc/<var>package</var></file>
6822 and can be referred to as
6823 <example compact="compact">
6824 http://localhost/doc/<var>package</var>/<var>filename</var>
6828 The web server should restrict access to the document
6829 tree so that only clients on the same host can read
6830 the documents. If the web server does not support such
6831 access controls, then it should not provide access at
6832 all, or ask about providing access during installation.
6836 <item><p>Web Document Root</p>
6839 Web Applications should try to avoid storing files in
6840 the Web Document Root. Instead they should use the
6841 /usr/share/doc/<var>package</var> directory for
6842 documents and register the Web Application via the
6843 menu package. If access to the web document root is
6844 unavoidable then use
6845 <example compact="compact">
6848 as the Document Root. This might be just a symbolic
6849 link to the location where the system administrator
6850 has put the real document root.
6854 </enumlist></p></sect>
6857 <sect id="mail-transport-agents">
6858 <heading>Mail transport, delivery and user agents</heading>
6861 Debian packages which process electronic mail, whether mail
6862 user agents (MUAs) or mail transport agents (MTAs), must
6863 ensure that they are compatible with the configuration
6864 decisions below. Failure to do this may result in lost
6865 mail, broken <tt>From:</tt> lines, and other serious brain
6870 The mail spool is <file>/var/mail</file> and the interface to
6871 send a mail message is <file>/usr/sbin/sendmail</file> (as per
6872 the FHS). On older systems, the mail spool may be
6873 physically located in <file>/var/spool/mail</file>, but all
6874 access to the mail spool should be via the
6875 <file>/var/mail</file> symlink. The mail spool is part of the
6876 base system and not part of the MTA package.
6880 All Debian MUAs, MTAs, MDAs and other mailbox accessing
6881 programs (such as IMAP daemons) must lock the mailbox in an
6882 NFS-safe way. This means that <tt>fcntl()</tt> locking must
6883 be combined with dot locking. To avoid deadlocks, a program
6884 should use <tt>fcntl()</tt> first and dot locking after
6885 this, or alternatively implement the two locking methods in
6886 a non blocking way<footnote>
6888 If it is not possible to establish both locks, the
6889 system shouldn't wait for the second lock to be
6890 established, but remove the first lock, wait a (random)
6891 time, and start over locking again.
6893 </footnote>. Using the functions <tt>maillock</tt> and
6894 <tt>mailunlock</tt> provided by the
6895 <tt>liblockfile*</tt><footnote>
6897 You will need to depend on <tt>liblockfile1
6898 (>>1.01)</tt> to use these functions.
6900 </footnote> packages is the recommended way to realize this.
6904 Mailboxes are generally mode 660
6905 <tt><var>user</var>.mail</tt> unless the system
6906 administrator has chosen otherwise. A MUA may remove a
6907 mailbox (unless it has nonstandard permissions) in which
6908 case the MTA or another MUA must recreate it if needed.
6909 Mailboxes must be writable by group mail.
6913 The mail spool is 2775 <tt>root.mail</tt>, and MUAs should
6914 be setgid mail to do the locking mentioned above (and
6915 must obviously avoid accessing other users' mailboxes
6916 using this privilege).</p>
6919 <file>/etc/aliases</file> is the source file for the system mail
6920 aliases (e.g., postmaster, usenet, etc.), it is the one
6921 which the sysadmin and <prgn>postinst</prgn> scripts may
6922 edit. After <file>/etc/aliases</file> is edited the program or
6923 human editing it must call <prgn>newaliases</prgn>. All MTA
6924 packages must come with a <prgn>newaliases</prgn> program,
6925 even if it does nothing, but older MTA packages did not do
6926 this so programs should not fail if <prgn>newaliases</prgn>
6927 cannot be found. Note that because of this, all MTA
6928 packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
6929 <tt>Replaces: mail-transport-agent</tt> control file
6934 The convention of writing <tt>forward to
6935 <var>address</var></tt> in the mailbox itself is not
6936 supported. Use a <tt>.forward</tt> file instead.</p>
6939 The <prgn>rmail</prgn> program used by UUCP
6940 for incoming mail should be <file>/usr/sbin/rmail</file>.
6941 Likewise, <prgn>rsmtp</prgn>, for receiving
6942 batch-SMTP-over-UUCP, should be <file>/usr/sbin/rsmtp</file> if it
6946 If your package needs to know what hostname to use on (for
6947 example) outgoing news and mail messages which are generated
6948 locally, you should use the file <file>/etc/mailname</file>. It
6949 will contain the portion after the username and <tt>@</tt>
6950 (at) sign for email addresses of users on the machine
6951 (followed by a newline).
6955 Such package should check for the existence of this file
6956 when it is being configured. If it exists, it should be
6957 used without comment, although an MTA's configuration script
6958 may wish to prompt the user even if it finds that this file
6959 exists. If the file does not exist, the package should
6960 prompt the user for the value (preferably using
6961 <prgn>debconf</prgn>) and store it in <file>/etc/mailname</file>
6962 as well as using it in the package's configuration. The
6963 prompt should make it clear that the name will not just be
6964 used by that package. For example, in this situation the
6965 <tt>inn</tt> package could say something like:
6966 <example compact="compact">
6967 Please enter the "mail name" of your system. This is the
6968 hostname portion of the address to be shown on outgoing
6969 news and mail messages. The default is
6970 <var>syshostname</var>, your system's host name. Mail
6971 name ["<var>syshostname</var>"]:
6973 where <var>syshostname</var> is the output of <tt>hostname
6979 <heading>News system configuration</heading>
6982 All the configuration files related to the NNTP (news)
6983 servers and clients should be located under
6984 <file>/etc/news</file>.</p>
6987 There are some configuration issues that apply to a number
6988 of news clients and server packages on the machine. These
6992 <tag><file>/etc/news/organization</file></tag>
6993 <item><p>A string which should appear as the
6994 organization header for all messages posted
6995 by NNTP clients on the machine</p></item>
6997 <tag><file>/etc/news/server</file></tag>
6998 <item><p>Contains the FQDN of the upstream NNTP
6999 server, or localhost if the local machine is
7000 an NNTP server.</p></item>
7003 Other global files may be added as required for cross-package news
7004 configuration.</p></sect>
7008 <heading>Programs for the X Window System</heading>
7011 <heading>Providing X support and package priorities</heading>
7014 Programs that can be configured with support for the X
7015 Window System must be configured to do so and must declare
7016 any package dependencies necessary to satisfy their
7017 runtime requirements when using the X Window System. If
7018 such a package is of higher priority than the X packages
7019 on which it depends, it is required that either the
7020 X-specific components be split into a separate package, or
7021 that an alternative version of the package, which includes
7022 X support, be provided, or that the package's priority be
7028 <heading>Packages providing an X server</heading>
7031 Packages that provide an X server that, directly or
7032 indirectly, communicates with real input and display
7033 hardware should declare in their control data that they
7034 provide the virtual package <tt>xserver</tt>.<footnote>
7036 This implements current practice, and provides an
7037 actual policy for usage of the <tt>xserver</tt>
7038 virtual package which appears in the virtual packages
7039 list. In a nutshell, X servers that interface
7040 directly with the display and input hardware or via
7041 another subsystem (e.g., GGI) should provide
7042 <tt>xserver</tt>. Things like <tt>Xvfb</tt>,
7043 <tt>Xnest</tt>, and <tt>Xprt</tt> should not.
7050 <heading>Packages providing a terminal emulator</heading>
7053 Packages that provide a terminal emulator for the X Window
7054 System which meet the criteria listed below should declare
7055 in their control data that they provide the virtual
7056 package <tt>x-terminal-emulator</tt>. They should also
7057 register themselves as an alternative for
7058 <file>/usr/bin/x-terminal-emulator</file>, with a priority of
7063 To be an <tt>x-terminal-emulator</tt>, a program must:
7064 <list compact="compact">
7066 Be able to emulate a DEC VT100 terminal, or a
7067 compatible terminal.
7071 Support the command-line option <tt>-e
7072 <var>command</var></tt>, which creates a new
7073 terminal window<footnote>
7075 "New terminal window" does not necessarily mean
7076 a new top-level X window directly parented by
7077 the window manager; it could, if the terminal
7078 emulator application were so coded, be a new
7079 "view" in a multiple-document interface (MDI).
7082 and runs the specified <var>command</var>,
7083 interpreting the entirity of the rest of the command
7084 line as a command to pass straight to exec, in the
7085 manner that <tt>xterm</tt> does.
7089 Support the command-line option <tt>-T
7090 <var>title</var></tt>, which creates a new terminal
7091 window with the window title <var>title</var>.
7098 <heading>Packages providing a window manager</heading>
7101 Packages that provide a window manager should declare in
7102 their control data that they provide the virtual package
7103 <tt>x-window-manager</tt>. They should also register
7104 themselves as an alternative for
7105 <file>/usr/bin/x-window-manager</file>, with a priority
7106 calculated as follows:
7107 <list compact="compact">
7108 <item><p>Start with a priority of 20.</p></item>
7112 If the window manager supports the Debian menu
7113 system, add 20 points if this support is available
7114 in the package's default configuration (i.e., no
7115 configuration files belonging to the system or user
7116 have to be edited to activate the feature); if
7117 configuration files must be modified, add only 10
7123 If the window manager complies with <url
7124 id="http://www.freedesktop.org/standards/wm-spec.html"
7125 name="The Window Manager Specification Project">,
7126 written by the <url id="http://www.freedesktop.org"
7127 name="Free Desktop Group">, add 40 points.
7133 If the window manager permits the X session to be
7134 restarted using a <em>different</em> window manager
7135 (without killing the X server) in its default
7136 configuration, add 10 points; otherwise add none.
7144 <heading>Packages providing fonts</heading>
7147 Packages that provide fonts for the X Window
7150 For the purposes of Debian Policy, a "font for the X
7151 Window System" is one which is accessed via X protocol
7152 requests. Fonts for the Linux console, for PostScript
7153 renderers, or any other purpose, do not fit this
7154 definition. Any tool which makes such fonts available
7155 to the X Window System, however, must abide by this
7159 must do a number of things to ensure that they are both
7160 available without modification of the X or font server
7161 configuration, and that they do not corrupt files used by
7162 other font packages to register information about
7167 Fonts of any type supported by the X Window System
7168 must be in a separate binary package from any
7169 executables, libraries, or documentation (except
7170 that specific to the fonts shipped, such as their
7171 license information). If one or more of the fonts
7172 so packaged are necessary for proper operation of
7173 the package with which they are associated the font
7174 package may be Recommended; if the fonts merely
7175 provide an enhancement, a Suggests relationship may
7176 be used. Packages must not Depend on font
7179 This is because the X server may retrieve fonts
7180 from the local filesystem or over the network
7181 from an X font server; the Debian package system
7182 is empowered to deal only with the local
7191 BDF fonts must be converted to PCF fonts with the
7192 <prgn>bdftopcf</prgn> utility (available in the
7193 <tt>xutils</tt> package, <prgn>gzip</prgn>ped, and
7194 placed in a directory that corresponds to their
7196 <list compact="compact">
7198 100 dpi fonts must be placed in
7199 <file>/usr/X11R6/lib/X11/fonts/100dpi/</file>.
7203 75 dpi fonts must be placed in
7204 <file>/usr/X11R6/lib/X11/fonts/75dpi/</file>.
7208 Character-cell fonts, cursor fonts, and other
7209 low-resolution fonts must be placed in
7210 <file>/usr/X11R6/lib/X11/fonts/misc/</file>.
7217 Speedo fonts must be placed in
7218 <file>/usr/X11R6/lib/X11/fonts/Speedo/</file>.
7222 Type 1 fonts must be placed in
7223 <file>/usr/X11R6/lib/X11/fonts/Type1/</file>. If font
7224 metric files are available, they must be placed here
7230 Subdirectories of <file>/usr/X11R6/lib/X11/fonts/</file>
7231 other than those listed above must be neither
7232 created nor used. (The <file>PEX</file>, <file>CID</file>,
7233 and <file>cyrillic</file> directories are excepted for
7234 historical reasons, but installation of files into
7235 these directories remains discouraged.)
7241 Font packages may, instead of placing files directly
7242 in the X font directories listed above, provide
7243 symbolic links in that font directory pointing to
7244 the files' actual location in the filesystem. Such
7245 a location must comply with the FHS.
7251 Font packages should not contain both 75dpi and
7252 100dpi versions of a font. If both are available,
7253 they should be provided in separate binary packages
7254 with <tt>-75dpi</tt> or <tt>-100dpi</tt> appended to
7255 the names of the packages containing the
7256 corresponding fonts.
7262 Fonts destined for the <file>misc</file> subdirectory
7263 should not be included in the same package as 75dpi
7264 or 100dpi fonts; instead, they should be provided in
7265 a separate package with <tt>-misc</tt> appended to
7272 Font packages must not provide the files
7273 <file>fonts.dir</file>, <file>fonts.alias</file>, or
7274 <file>fonts.scale</file> in a font directory:
7277 <file>fonts.dir</file> files must not be provided at all.
7282 <file>fonts.alias</file> and <file>fonts.scale</file>
7283 files, if needed, should be provided in the
7285 <file>/etc/X11/fonts/<var>fontdir</var>/<var>package</var>.<var>extension</var></file>,
7286 where <var>fontdir</var> is the name of the
7288 <file>/usr/X11R6/lib/X11/fonts/</file> where the
7289 package's corresponding fonts are stored
7290 (e.g., <tt>75dpi</tt> or <tt>misc</tt>),
7291 <var>package</var> is the name of the package
7292 that provides these fonts, and
7293 <var>extension</var> is either <tt>scale</tt>
7294 or <tt>alias</tt>, whichever corresponds to
7304 Font packages must declare a dependency on
7305 <tt>xutils (>> 4.0.3)</tt> in their control
7312 Font packages that provide one or more
7313 <file>fonts.scale</file> files as described above must
7314 invoke <prgn>update-fonts-scale</prgn> on each
7315 directory into which they installed fonts
7316 <em>before</em> invoking
7317 <prgn>update-fonts-dir</prgn> on that directory.
7318 This invocation must occur in both the
7319 <prgn>postinst</prgn> (for all arguments) and
7320 <prgn>postrm</prgn> (for all arguments except
7321 <tt>upgrade</tt>) scripts.
7327 Font packages that provide one or more
7328 <file>fonts.alias</file> files as described above must
7329 invoke <prgn>update-fonts-alias</prgn> on each
7330 directory into which they installed fonts. This
7331 invocation must occur in both the
7332 <prgn>postinst</prgn> (for all arguments) and
7333 <prgn>postrm</prgn> (for all arguments except
7334 <tt>upgrade</tt>) scripts.
7340 Font packages must invoke
7341 <prgn>update-fonts-dir</prgn> on each directory into
7342 which they installed fonts. This invocation must
7343 occur in both the <prgn>postinst</prgn> (for all
7344 arguments) and <prgn>postrm</prgn> (for all
7345 arguments except <tt>upgrade</tt>) scripts.
7351 Font packages must not provide alias names for the
7352 fonts they include which collide with alias names
7353 already in use by fonts already packaged.
7359 Font packages must not provide fonts with the same
7360 XLFD registry name as another font already packaged.
7368 <heading>Application defaults files</heading>
7371 Application defaults files must be installed in the
7372 directory <file>/etc/X11/app-defaults/</file> (use of a
7373 localized subdirectory of <file>/etc/X11/</file> as described
7374 in the <em>X Toolkit Intrinsics - C Language
7375 Interface</em> manual is also permitted). They must be
7376 registered as <tt>conffile</tt>s or handled as
7377 configuration files. Packages must not provide the
7378 directory <file>/usr/X11R6/lib/X11/app-defaults/</file>.
7382 Customization of programs' X resources may also be
7383 supported with the provision of a file with the same name
7384 as that of the package placed in the
7385 <file>/etc/X11/Xresources/</file> directory, which must
7386 registered as a <tt>conffile</tt> or handled as a
7387 configuration file.<footnote>
7389 Note that this mechanism is not the same as using
7390 app-defaults; app-defaults are tied to the client
7391 binary on the local filesystem, whereas X resources
7392 are stored in the X server and affect all connecting
7396 <em>Important:</em> packages that install files into the
7397 <file>/etc/X11/Xresources/</file> directory must conflict with
7398 <tt>xbase (<< 3.3.2.3a-2)</tt>; if this is not done
7399 it is possible for the installing package to destroy a
7400 previously-existing <file>/etc/X11/Xresources</file> file
7401 which had been customized by the system administrator.
7406 <heading>Installation directory issues</heading>
7409 Packages using the X Window System should not be
7410 configured to install files under the <file>/usr/X11R6/</file>
7411 directory unless they use <prgn>imake</prgn>. The
7412 <file>/usr/X11R6/</file> directory hierarchy should be
7413 regarded as deprecated for all packages except the X
7414 Window System itself, and those which use the
7415 <prgn>imake</prgn> program it provides, in which case the
7416 packages may transition out of the <file>/usr/X11R6/</file>
7417 directory at the maintainer's discretion.<footnote>
7419 <prgn>Imake</prgn>-using programs are exempt because,
7420 as long as they are written correctly, the pathnames
7421 they use to locate resources and install themselves
7422 are derived wholly from the X Window System
7423 configuration. Thus, in the event that the X Window
7424 System moves to <file>/usr/X11R7/</file>,
7425 <file>/usr/X12/</file>, or just plain <file>/usr/</file>, all
7426 that is required for these programs is a recompile
7427 against the corresponding X Window System library
7428 development packages.
7431 Programs that use GNU <prgn>autoconf</prgn> and
7432 <prgn>automake</prgn> are usually easily configured at
7433 compile time to use <file>/usr/</file> instead of
7434 <file>/usr/X11R6/</file>, and this should be done whenever
7435 possible. Configuration files for window managers and
7436 display managers should be placed in a subdirectory of
7437 <file>/etc/X11/</file> corresponding to the package name due
7438 to these programs' tight integration with the mechanisms
7439 of the X Window System. Application-level programs should
7440 use the <file>/etc/</file> directory unless otherwise mandated
7441 by policy. The installation of files into subdirectories
7442 of <file>/usr/X11R6/include/X11/</file> and
7443 <file>/usr/X11R6/lib/X11/</file> is permitted but discouraged;
7444 package maintainers should determine if subdirectories of
7445 <file>/usr/lib/</file> and <file>/usr/share/</file> can be used
7446 instead. (The use of symbolic links from the
7447 <file>X11R6</file> directories to other FHS-compliant
7448 locations is encouraged if the program is not easily
7449 configured to look elsewhere for its files.) Packages
7450 must not provide or install files into the directories
7451 <file>/usr/bin/X11/</file>, <file>/usr/include/X11/</file> or
7452 <file>/usr/lib/X11/</file>. Files within a package should,
7453 however, make reference to these directories, rather than
7454 their <tt>X11R6</tt>-named counterparts
7455 <file>/usr/X11R6/bin/</file>, <file>/usr/X11R6/include/X11/</file>
7456 and <file>/usr/X11R6/lib/X11/</file>, if the resources being
7457 referred to have not been moved to other FHS-compliant
7463 <heading>The OSF/Motif and OpenMotif libraries</heading>
7466 <em>Programs that require the non-DFSG-compliant OSF/Motif or
7467 OpenMotif libraries</em><footnote>
7469 OSF/Motif and OpenMotif are collectively referred to as
7470 "Motif" in this policy document.
7473 should be compiled against and tested with LessTif (a free
7474 re-implementation of Motif) instead. If the maintainer
7475 judges that the program or programs do not work
7476 sufficiently well with LessTif to be distributed and
7477 supported, but do so when compiled against Motif, then two
7478 versions of the package should be created; one linked
7479 statically against Motif and with <tt>-smotif</tt>
7480 appended to the package name, and one linked dynamically
7481 against Motif and with <tt>-dmotif</tt> appended to the
7482 package name. Both Motif-linked versions are dependent
7483 upon non-DFSG-compliant software and thus cannot be
7484 uploaded to the <em>main</em> distribution; if the
7485 software is itself DFSG-compliant it may be uploaded to
7486 the <em>contrib</em> distribution. While known existing
7487 versions of Motif permit unlimited redistribution of
7488 binaries linked against the library (whether statically or
7489 dynamically), it is the package maintainer's
7490 responsibility to determine whether this is permitted by
7491 the license of the copy of Motif in his or her possession.
7497 <heading>Perl programs and modules</heading>
7500 Perl programs and modules should follow the current Perl policy.
7504 The Perl policy can be found in the <tt>perl-policy</tt>
7505 files in the <tt>debian-policy</tt> package.
7506 They are also available from the Debian web mirrors at
7507 <tt><url name="/doc/packaging-manuals/perl-policy/"
7508 id="http://www.debian.org/doc/packaging-manuals/perl-policy/"></tt>
7509 and from the Debian archive mirrors at
7510 <tt><url name="/doc/package-developer/perl-policy.txt.gz"
7511 id="http://ftp.debian.org/debian/doc/package-developer/perl-policy.txt.gz"></tt>.
7516 <heading>Emacs lisp programs</heading>
7519 Please refer to the "Debian Emacs Policy" for details of how to
7520 package emacs lisp programs.
7524 The Emacs policy is available in
7525 <file>debian-emacs-policy.gz</file> of the
7526 <package>emacsen-common</package> package.
7527 It is also available from the Debian web mirrors at
7528 <tt><url name="/doc/packaging-manuals/debian-emacs-policy"
7529 id="http://www.debian.org/doc/packaging-manuals/debian-emacs-policy"></tt>.
7534 <heading>Games</heading>
7537 The permissions on <file>/var/games</file> are mode 755, owner
7538 <tt>root</tt> and group <tt>root</tt>.
7542 Each game decides on its own security policy.</p>
7545 Games which require protected, privileged access to
7546 high-score files, savegames, etc., may be made
7547 set-<em>group</em>-id (mode 2755) and owned by
7548 <tt>root.games</tt>, and use files and directories with
7549 appropriate permissions (770 <tt>root.games</tt>, for
7550 example). They must not be made
7551 set-<em>user</em>-id, as this causes security problems. (If
7552 an attacker can subvert any set-user-id game they can
7553 overwrite the executable of any other, causing other players
7554 of these games to run a Trojan horse program. With a
7555 set-group-id game the attacker only gets access to less
7556 important game data, and if they can get at the other
7557 players' accounts at all it will take considerably more
7561 Some packages, for example some fortune cookie programs, are
7562 configured by the upstream authors to install with their
7563 data files or other static information made unreadable so
7564 that they can only be accessed through set-id programs
7565 provided. You should not do this in a Debian package: anyone can
7566 download the <file>.deb</file> file and read the data from it,
7567 so there is no point making the files unreadable. Not
7568 making the files unreadable also means that you don't have
7569 to make so many programs set-id, which reduces the risk of a
7573 As described in the FHS, binaries of games should be
7574 installed in the directory <file>/usr/games</file>. This also
7575 applies to games that use the X Window System. Manual pages
7576 for games (X and non-X games) should be installed in
7577 <file>/usr/share/man/man6</file>.</p>
7581 <chapt id="docs"><heading>Documentation</heading>
7585 <heading>Manual pages</heading>
7588 You should install manual pages in <prgn>nroff</prgn> source
7589 form, in appropriate places under <file>/usr/share/man</file>.
7590 You should only use sections 1 to 9 (see the FHS for more
7591 details). You must not install a preformatted "cat page".
7595 Each program, utility, and function should have an
7596 associated manual page included in the same package. It is
7597 suggested that all configuration files also have a manual
7598 page included as well. Manual pages for protocols and other
7599 auxiliary things are optional.
7603 If no manual page is available, this is considered as a bug
7604 and should be reported to the Debian Bug Tracking System (the
7605 maintainer of the package is allowed to write this bug report
7606 themselves, if they so desire). Do not close the bug report
7607 until a proper manpage is available.<footnote>
7609 It is not very hard to write a man page. See the
7610 <url id="http://www.schweikhardt.net/man_page_howto.html"
7611 name="Man-Page-HOWTO">,
7612 <manref name="man" section="7">, the examples
7613 created by <prgn>debmake</prgn> or <prgn>dh_make</prgn>,
7614 the helper programs <prgn>help2man</prgn>, or the
7615 directory <file>/usr/share/doc/man-db/examples</file>.
7621 You may forward a complaint about a missing manpage to the
7622 upstream authors, and mark the bug as forwarded in the
7623 Debian bug tracking system. Even though the GNU Project do
7624 not in general consider the lack of a manpage to be a bug,
7625 we do; if they tell you that they don't consider it a bug
7626 you should leave the bug in our bug tracking system open
7631 Manual pages should be installed compressed using <tt>gzip -9</tt>.
7635 If one manpage needs to be accessible via several names it
7636 is better to use a symbolic link than the <file>.so</file>
7637 feature, but there is no need to fiddle with the relevant
7638 parts of the upstream source to change from <file>.so</file> to
7639 symlinks: don't do it unless it's easy. You should not
7640 create hard links in the manual page directories, nor put
7641 absolute filenames in <file>.so</file> directives. The filename
7642 in a <file>.so</file> in a manpage should be relative to the
7643 base of the manpage tree (usually
7644 <file>/usr/share/man</file>). If you do not create any links
7645 (whether symlinks, hard links, or <tt>.so</tt> directives)
7646 in the filesystem to the alternate names of the manpage,
7647 then you should not rely on <prgn>man</prgn> finding your
7648 manpage under those names based solely on the information in
7649 the manpage's header.<footnote>
7651 Supporting this in <prgn>man</prgn> often requires
7652 unreasonable processing time to find a manual page or to
7653 report that none exists, and moves knowledge into man's
7654 database that would be better left in the filesystem.
7655 This support is therefore deprecated and will cease to
7656 be present in the future.
7663 <heading>Info documents</heading>
7666 Info documents should be installed in <file>/usr/share/info</file>.
7667 They should be compressed with <tt>gzip -9</tt>.
7671 Your package should call <prgn>install-info</prgn> to update
7672 the Info <file>dir</file> file in its <prgn>postinst</prgn>
7673 script when called with a <tt>configure</tt> argument, for
7675 <example compact="compact">
7676 install-info --quiet --section Development Development \
7677 /usr/share/info/foobar.info
7681 It is a good idea to specify a section for the location of
7682 your program; this is done with the <tt>--section</tt>
7683 switch. To determine which section to use, you should look
7684 at <file>/usr/share/info/dir</file> on your system and choose the most
7685 relevant (or create a new section if none of the current
7686 sections are relevant). Note that the <tt>--section</tt>
7687 flag takes two arguments; the first is a regular expression
7688 to match (case-insensitively) against an existing section,
7689 the second is used when creating a new one.</p>
7692 You should remove the entries in the <prgn>prerm</prgn>
7693 script when called with a <tt>remove</tt> argument:
7694 <example compact="compact">
7695 install-info --quiet --remove /usr/share/info/foobar.info
7699 If <prgn>install-info</prgn> cannot find a description entry
7700 in the Info file you must supply one. See <manref
7701 name="install-info" section="8"> for details.</p>
7705 <heading>Additional documentation</heading>
7708 Any additional documentation that comes with the package may
7709 be installed at the discretion of the package maintainer.
7710 Text documentation should be installed in the directory
7711 <file>/usr/share/doc/<var>package</var></file>, where
7712 <var>package</var> is the name of the package, and
7713 compressed with <tt>gzip -9</tt> unless it is small.
7717 If a package comes with large amounts of documentation which
7718 many users of the package will not require you should create
7719 a separate binary package to contain it, so that it does not
7720 take up disk space on the machines of users who do not need
7721 or want it installed.</p>
7724 It is often a good idea to put text information files
7725 (<file>README</file>s, changelogs, and so forth) that come with
7726 the source package in <file>/usr/share/doc/<var>package</var></file>
7727 in the binary package. However, you don't need to install
7728 the instructions for building and installing the package, of
7732 Packages must not require the existance of any files in
7733 <file>/usr/share/doc/</file> in order to function
7736 The system administrator should be able to
7737 delete files in <file>/usr/share/doc/</file> without causing
7738 any programs to break.
7741 Any files that are referenced by programs but are also
7742 useful as standalone documentation should be installed under
7743 <file>/usr/share/<var>package</var>/</file> with symbolic links from
7744 <file>/usr/share/doc/<var>package</var></file>.
7748 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
7749 link to another directory in <file>/usr/share/doc</file> only if
7750 the two packages both come from the same source and the
7751 first package Depends on the second.
7755 Former Debian releases placed all additional documentation
7756 in <file>/usr/doc/<var>package</var></file>. This has been
7757 changed to <file>/usr/share/doc/<var>package</var></file>,
7758 and packages must not put documentation in the directory
7759 <file>/usr/doc/<var>package</var></file>. <footnote>
7760 <p>At this phase of the transition, we no longer require a
7761 symbolic link in <file>/usr/doc/</file>. At a later point,
7762 policy shall change to make the symbolic links a bug.</p>
7768 <heading>Preferred documentation formats</heading>
7771 The unification of Debian documentation is being carried out
7775 If your package comes with extensive documentation in a
7776 markup format that can be converted to various other formats
7777 you should if possible ship HTML versions in a binary
7778 package, in the directory
7779 <file>/usr/share/doc/<var>appropriate-package</var></file> or
7780 its subdirectories.<footnote>
7782 The rationale: The important thing here is that HTML
7783 docs should be available in <em>some</em> package, not
7784 necessarily in the main binary package.
7790 Other formats such as PostScript may be provided at the
7791 package maintainer's discretion.
7795 <sect id="copyrightfile">
7796 <heading>Copyright information</heading>
7799 Every package must be accompanied by a verbatim copy of its
7800 copyright and distribution license in the file
7801 <file>/usr/share/doc/<var>package</var>/copyright</file>. This
7802 file must neither be compressed nor be a symbolic link.
7806 In addition, the copyright file must say where the upstream
7807 sources (if any) were obtained. It should name the original
7808 authors of the package and the Debian maintainer(s) who were
7809 involved with its creation.</p>
7812 A copy of the file which will be installed in
7813 <file>/usr/share/doc/<var>package</var>/copyright</file> should
7814 be in <file>debian/copyright</file> in the source package.
7818 <file>/usr/share/doc/<var>package</var></file> may be a symbolic
7819 link to another directory in <file>/usr/share/doc</file> only if
7820 the two packages both come from the same source and the
7821 first package Depends on the second. These rules are
7822 important because copyrights must be extractable by
7827 Packages distributed under the UCB BSD license, the Artistic
7828 license, the GNU GPL, and the GNU LGPL should refer to the
7829 files <file>/usr/share/common-licenses/BSD</file>,
7830 <file>/usr/share/common-licenses/Artistic</file>,
7831 <file>/usr/share/common-licenses/GPL</file>, and
7832 <file>/usr/share/common-licenses/LGPL</file> respectively,
7833 rather than quoting them in the copyright file.
7837 You should not use the copyright file as a general <file>README</file>
7838 file. If your package has such a file it should be
7839 installed in <file>/usr/share/doc/<var>package</var>/README</file> or
7840 <file>README.Debian</file> or some other appropriate place.</p>
7844 <heading>Examples</heading>
7847 Any examples (configurations, source files, whatever),
7848 should be installed in a directory
7849 <file>/usr/share/doc/<var>package</var>/examples</file>. These
7850 files should not be referenced by any program: they're there
7851 for the benefit of the system administrator and users as
7852 documentation only. Architecture-specific example files
7853 should be installed in a directory
7854 <file>/usr/lib/<var>package</var>/examples</file> with symbolic
7856 <file>/usr/share/doc/<var>package</var>/examples</file>, or the
7857 latter directory itself may be a symbolic link to the
7862 If the purpose of a package is to provide examples, then the
7863 example files may be installed into
7864 <file>/usr/share/doc/<var>package</var></file>.
7868 <sect id="changelogs">
7869 <heading>Changelog files</heading>
7872 The Debian changelog file (<file>debian/changelog</file>) should
7873 explain briefly what modifications were made in the Debian version
7874 of the package compared to the upstream one. Other changes and
7875 updates to the package should also be documented in this file.
7879 Mistakes in changelogs are usually best rectified by
7880 making a new changelog entry rather than "rewriting history"
7881 by editing old changelog entries.
7885 The format of the <file>debian/changelog</file> file is described
7886 in <ref id="dpkgchangelog">. In non-experimental packages you must
7887 use a format for <file>debian/changelog</file> which is supported
7888 by the most recent released version of <prgn>dpkg</prgn>.<footnote>
7890 If you wish to use an alternative format, you may do so as
7891 long as you include a parser for it in your source package.
7892 The parser must have an API compatible with that expected by
7893 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-gencontrol</prgn>.
7894 If there is general interest in the new format, you should
7895 contact the <package>dpkg</package> maintainer to have the
7896 parser script for it included in the <prgn>dpkg</prgn>
7897 package. (You will need to agree that the parser and its
7898 manpage may be distributed under the GNU GPL, just as the rest
7899 of <prgn>dpkg</prgn> is.)
7905 Packages that are not Debian-native must contain a
7906 compressed copy of the <file>debian/changelog</file> file from
7907 the Debian source tree in
7908 <file>/usr/share/doc/<var>package</var></file> with the name
7909 <file>changelog.Debian.gz</file>.
7913 If an upstream changelog is available, it should be accessible as
7914 <file>/usr/share/doc/<var>package</var>/changelog.gz</file> in
7915 plain text. If the upstream changelog is distributed in
7916 HTML, it should be made available in that form as
7917 <file>/usr/share/doc/<var>package</var>/changelog.html.gz</file>
7918 and a plain text <file>changelog.gz</file> should be generated
7919 from it using, for example, <tt>lynx -dump -nolist</tt>. If
7920 the upstream changelog files do not already conform to this
7921 naming convention, then this may be achieved either by
7922 renaming the files, or by adding a symbolic link, at the
7923 maintainer's discretion.<footnote>
7925 Rationale: People should not have to look in places for
7926 upstream changelogs merely because they are given
7927 different names or are distributed in HTML format.
7933 All of these files should be installed compressed using
7934 <tt>gzip -9</tt>, as they will become large with time even
7935 if they start out small.
7939 If the package has only one changelog which is used both as
7940 the Debian changelog and the upstream one because there is
7941 no separate upstream maintainer then that changelog should
7942 usually be installed as
7943 <file>/usr/share/doc/<var>package</var>/changelog.gz</file>; if
7944 there is a separate upstream maintainer, but no upstream
7945 changelog, then the Debian changelog should still be called
7946 <file>changelog.Debian.gz</file>.</p>
7951 <appendix id="pkg-scope">
7952 <heading>Introduction and scope of these appendices</heading>
7955 These appendices are taken essentially verbatim from the
7956 now-deprecated Packaging Manual, version 3.2.1.0. They are
7957 the chapters which are likely to be of use to package
7958 maintainers and which have not already been included in the
7959 policy document itself. Most of these sections are very likely
7960 not relevant to policy; they should be treated as
7961 documentation for the packaging system. Please note that these
7962 appendices are included for convenience, and for historical
7963 reasons: they used to be part of policy package, and they have
7964 not yet been incorporated into dpkg documentation. However,
7965 they still have value, and hence they are presented here.
7968 They have not yet been checked to ensure that they are
7969 compatible with the contents of policy, and if there are any
7970 contradictions, the version in the main policy document takes
7971 precedence. The remaining chapters of the old Packaging
7972 Manual have also not been read in detail to ensure that there
7973 are not parts which have been left out. Both of these will be
7978 <prgn>dpkg</prgn> is a suite of programs for creating binary
7979 package files and installing and removing them on Unix
7982 <prgn>dpkg</prgn> is targetted primarily at Debian
7983 GNU/Linux, but may work on or be ported to other
7990 The binary packages are designed for the management of
7991 installed executable programs (usually compiled binaries) and
7992 their associated data, though source code examples and
7993 documentation are provided as part of some packages.</p>
7996 This manual describes the technical aspects of creating Debian
7997 binary packages (<file>.deb</file> files). It documents the
7998 behaviour of the package management programs
7999 <prgn>dpkg</prgn>, <prgn>dselect</prgn> et al. and the way
8000 they interact with packages.</p>
8003 It also documents the interaction between
8004 <prgn>dselect</prgn>'s core and the access method scripts it
8005 uses to actually install the selected packages, and describes
8006 how to create a new access method.</p>
8009 This manual does not go into detail about the options and
8010 usage of the package building and installation tools. It
8011 should therefore be read in conjuction with those programs'
8016 The utility programs which are provided with <prgn>dpkg</prgn>
8017 for managing various system configuration and similar issues,
8018 such as <prgn>update-rc.d</prgn> and
8019 <prgn>install-info</prgn>, are not described in detail here -
8020 please see their manpages.
8024 It is assumed that the reader is reasonably familiar with the
8025 <prgn>dpkg</prgn> System Administrators' manual.
8026 Unfortunately this manual does not yet exist.
8030 The Debian version of the FSF's GNU hello program is provided
8031 as an example for people wishing to create Debian
8032 packages. The Debian <prgn>debmake</prgn> package is
8033 recommended as a very helpful tool in creating and maintaining
8034 Debian packages. However, while the tools and examples are
8035 helpful, they do not replace the need to read and follow the
8036 Policy and Programmer's Manual.</p>
8039 <appendix id="pkg-binarypkg"><heading>Binary packages (from old
8044 The binary package has two main sections. The first part
8045 consists of various control information files and scripts used
8046 by <prgn>dpkg</prgn> when installing and removing. See <ref
8047 id="pkg-controlarea">.
8051 The second part is an archive containing the files and
8052 directories to be installed.
8056 In the future binary packages may also contain other
8057 components, such as checksums and digital signatures. The
8058 format for the archive is described in full in the
8059 <file>deb(5)</file> manpage.
8063 <sect id="pkg-bincreating"><heading>Creating package files -
8064 <prgn>dpkg-deb</prgn>
8068 All manipulation of binary package files is done by
8069 <prgn>dpkg-deb</prgn>; it's the only program that has
8070 knowledge of the format. (<prgn>dpkg-deb</prgn> may be
8071 invoked by calling <prgn>dpkg</prgn>, as <prgn>dpkg</prgn>
8072 will spot that the options requested are appropriate to
8073 <prgn>dpkg-deb</prgn> and invoke that instead with the same
8078 In order to create a binary package you must make a
8079 directory tree which contains all the files and directories
8080 you want to have in the filesystem data part of the package.
8081 In Debian-format source packages this directory is usually
8082 <file>debian/tmp</file>, relative to the top of the package's
8087 They should have the locations (relative to the root of the
8088 directory tree you're constructing) ownerships and
8089 permissions which you want them to have on the system when
8094 With current versions of <prgn>dpkg</prgn> the uid/username
8095 and gid/groupname mappings for the users and groups being
8096 used should be the same on the system where the package is
8097 built and the one where it is installed.
8101 You need to add one special directory to the root of the
8102 miniature filesystem tree you're creating:
8103 <prgn>DEBIAN</prgn>. It should contain the control
8104 information files, notably the binary package control file
8105 (see <ref id="pkg-controlfile">).
8109 The <prgn>DEBIAN</prgn> directory will not appear in the
8110 filesystem archive of the package, and so won't be installed
8111 by <prgn>dpkg</prgn> when the package is installed.
8115 When you've prepared the package, you should invoke:
8117 dpkg --build <var>directory</var>
8122 This will build the package in
8123 <file><var>directory</var>.deb</file>. (<prgn>dpkg</prgn> knows
8124 that <tt>--build</tt> is a <prgn>dpkg-deb</prgn> option, so
8125 it invokes <prgn>dpkg-deb</prgn> with the same arguments to
8130 See the manpage <manref name="dpkg-deb" section="8"> for details of how
8131 to examine the contents of this newly-created file. You may find the
8132 output of following commands enlightening:
8134 dpkg-deb --info <var>filename</var>.deb
8135 dpkg-deb --contents <var>filename</var>.deb
8136 dpkg --contents <var>filename</var>.deb
8138 To view the copyright file for a package you could use this command:
8140 dpkg --fsys-tarfile <var>filename</var>.deb | tar xof usr/share/doc/<var>\*</var>copyright | less
8145 <sect id="pkg-controlarea">
8147 Package control information files
8151 The control information portion of a binary package is a
8152 collection of files with names known to <prgn>dpkg</prgn>.
8153 It will treat the contents of these files specially - some
8154 of them contain information used by <prgn>dpkg</prgn> when
8155 installing or removing the package; others are scripts which
8156 the package maintainer wants <prgn>dpkg</prgn> to run.
8160 It is possible to put other files in the package control
8161 area, but this is not generally a good idea (though they
8162 will largely be ignored).
8166 Here is a brief list of the control info files supported by
8167 <prgn>dpkg</prgn> and a summary of what they're used for.
8172 <tag><tt>control</tt>
8176 This is the key description file used by
8177 <prgn>dpkg</prgn>. It specifies the package's name
8178 and version, gives its description for the user,
8179 states its relationships with other packages, and so
8180 forth. See <ref id="pkg-controlfile">.
8184 It is usually generated automatically from information
8185 in the source package by the
8186 <prgn>dpkg-gencontrol</prgn> program, and with
8187 assistance from <prgn>dpkg-shlibdeps</prgn>. See <ref
8188 id="pkg-sourcetools">.</p>
8191 <tag><tt>postinst</tt>, <tt>preinst</tt>, <tt>postrm</tt>,
8197 These are exectuable files (usually scripts) which
8198 <prgn>dpkg</prgn> runs during installation, upgrade
8199 and removal of packages. They allow the package to
8200 deal with matters which are particular to that package
8201 or require more complicated processing than that
8202 provided by <prgn>dpkg</prgn>. Details of when and
8203 how they are called are in <ref
8204 id="maintainerscripts">.
8208 It is very important to make these scripts
8212 That means that if it runs successfully or fails
8213 and then you call it again it doesn't bomb out,
8214 but just ensures that everything is the way it
8217 </footnote> This is so that if an error occurs, the
8218 user interrupts <prgn>dpkg</prgn> or some other
8219 unforeseen circumstance happens you don't leave the
8220 user with a badly-broken package.
8224 The maintainer scripts are guaranteed to run with a
8225 controlling terminal and can interact with the user.
8226 If they need to prompt for passwords, do full-screen
8227 interaction or something similar you should do these
8228 things to and from <file>/dev/tty</file>, since
8229 <prgn>dpkg</prgn> will at some point redirect scripts'
8230 standard input and output so that it can log the
8231 installation process. Likewise, because these scripts
8232 may be executed with standard output redirected into a
8233 pipe for logging purposes, Perl scripts should set
8234 unbuffered output by setting <tt>$|=1</tt> so that the
8235 output is printed immediately rather than being
8240 Each script should return a zero exit status for
8241 success, or a nonzero one for failure.</p>
8244 <tag><tt>conffiles</tt>
8249 This file contains a list of configuration files which
8250 are to be handled automatically by <prgn>dpkg</prgn>
8251 (see <ref id="pkg-conffiles">). Note that not necessarily
8252 every configuration file should be listed here.</p>
8255 <tag><tt>shlibs</tt>
8260 This file contains a list of the shared libraries
8261 supplied by the package, with dependency details for
8262 each. This is used by <prgn>dpkg-shlibdeps</prgn>
8263 when it determines what dependencies are required in a
8264 package control file. The <tt>shlibs</tt> file format
8265 is described on <ref id="shlibs">.
8271 <sect id="pkg-controlfile">
8273 The main control information file: <tt>control</tt>
8276 The most important control information file used by
8277 <prgn>dpkg</prgn> when it installs a package is
8278 <tt>control</tt>. It contains all the package"s "vital
8283 The binary package control files of packages built from
8284 Debian sources are made by a special tool,
8285 <prgn>dpkg-gencontrol</prgn>, which reads
8286 <file>debian/control</file> and <file>debian/changelog</file> to
8287 find the information it needs. See <ref id="pkg-sourcepkg"> for
8292 The fields in binary package control files are:
8293 <list compact="compact">
8295 <p><qref id="pkg-f-Package"><tt>Package</tt></qref> (mandatory)</p>
8298 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
8300 <item><p><qref id="pkg-f-Architecture"><tt>Architecture</tt></qref>
8304 This field should appear in all packages, though
8305 <prgn>dpkg</prgn> doesn't require it yet so that
8306 old packages can still be installed.
8312 <p><qref id="relationships"><tt>Depends</tt>,
8313 <tt>Provides</tt> et al.</qref></p>
8316 <p><qref id="pkg-f-Essential"><tt>Essential</tt></qref></p>
8319 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
8322 <p><qref id="pkg-f-classification"><tt>Section</tt>,
8323 <tt>Priority</tt></qref></p>
8326 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
8329 <p><qref id="descriptions"><tt>Description</tt></qref></p>
8333 <qref id="pkg-f-Installed-Size"><tt>Installed-Size</tt></qref>
8339 A description of the syntax of control files and the purpose
8340 of these fields is available in <ref id="pkg-controlfields">.
8345 <heading>Time Stamps</heading>
8347 Maintainers are encouraged to preserve the modification
8348 times of the upstream source files in a package, as far as
8349 is reasonably possible.
8352 The rationale is that there is some information conveyed
8353 by knowing the age of the file, for example, you could
8354 recognize that some documentation is very old by looking
8355 at the modification time, so it would be nice if the
8356 modification time of the upstream source would be
8364 <appendix id="pkg-sourcepkg">
8365 <heading>Source packages (from old Packaging Manual) </heading>
8368 The Debian binary packages in the distribution are generated
8369 from Debian sources, which are in a special format to assist
8370 the easy and automatic building of binaries.
8373 <sect id="pkg-sourcetools">
8374 <heading>Tools for processing source packages</heading>
8377 Various tools are provided for manipulating source packages;
8378 they pack and unpack sources and help build of binary
8379 packages and help manage the distribution of new versions.
8383 They are introduced and typical uses described here; see
8384 <manref name="dpkg-source" section="1"> for full
8385 documentation about their arguments and operation.
8389 For examples of how to construct a Debian source package,
8390 and how to use those utilities that are used by Debian
8391 source packages, please see the <prgn>hello</prgn> example
8397 <prgn>dpkg-source</prgn> - packs and unpacks Debian source
8402 This program is frequently used by hand, and is also
8403 called from package-independent automated building scripts
8404 such as <prgn>dpkg-buildpackage</prgn>.
8408 To unpack a package it is typically invoked with
8410 dpkg-source -x <var>.../path/to/filename</var>.dsc
8415 with the <file><var>filename</var>.tar.gz</file> and
8416 <file><var>filename</var>.diff.gz</file> (if applicable) in
8417 the same directory. It unpacks into
8418 <file><var>package</var>-<var>version</var></file>, and if
8420 <file><var>package</var>-<var>version</var>.orig</file>, in
8421 the current directory.
8425 To create a packed source archive it is typically invoked:
8427 dpkg-source -b <var>package</var>-<var>version</var>
8432 This will create the <file>.dsc</file>, <file>.tar.gz</file> and
8433 <file>.diff.gz</file> (if appropriate) in the current
8434 directory. <prgn>dpkg-source</prgn> does not clean the
8435 source tree first - this must be done separately if it is
8440 See also <ref id="pkg-sourcearchives">.</p>
8446 <prgn>dpkg-buildpackage</prgn> - overall package-building
8451 <prgn>dpkg-buildpackage</prgn> is a script which invokes
8452 <prgn>dpkg-source</prgn>, the <file>debian/rules</file>
8453 targets <tt>clean</tt>, <tt>build</tt> and
8454 <tt>binary</tt>, <prgn>dpkg-genchanges</prgn> and
8455 <prgn>pgp</prgn> to build a signed source and binary
8460 It is usually invoked by hand from the top level of the
8461 built or unbuilt source directory. It may be invoked with
8462 no arguments; useful arguments include:
8463 <taglist compact="compact">
8464 <tag><tt>-uc</tt>, <tt>-us</tt></tag>
8467 Do not PGP-sign the <tt>.changes</tt> file or the
8468 source package <tt>.dsc</tt> file, respectively.</p>
8470 <tag><tt>-p<var>pgp-command</var></tt></tag>
8473 Invoke <var>pgp-command</var> instead of finding
8474 <tt>pgp</tt> on the <prgn>PATH</prgn>.
8475 <var>pgp-command</var> must behave just like
8476 <prgn>pgp</prgn>.</p>
8478 <tag><tt>-r<var>root-command</var></tt></tag>
8481 When root privilege is required, invoke the command
8482 <var>root-command</var>. <var>root-command</var>
8483 should invoke its first argument as a command, from
8484 the <prgn>PATH</prgn> if necessary, and pass its
8485 second and subsequent arguments to the command it
8486 calls. If no <var>root-command</var> is supplied
8487 then <var>dpkg-buildpackage</var> will take no
8488 special action to gain root privilege, so that for
8489 most packages it will have to be invoked as root to
8492 <tag><tt>-b</tt>, <tt>-B</tt></tag>
8495 Two types of binary-only build and upload - see
8496 <manref name="dpkg-source" section="1">.
8505 <prgn>dpkg-gencontrol</prgn> - generates binary package
8510 This program is usually called from <file>debian/rules</file>
8511 (see <ref id="pkg-sourcetree">) in the top level of the source
8516 This is usually done just before the files and directories in the
8517 temporary directory tree where the package is being built have their
8518 permissions and ownerships set and the package is constructed using
8519 <prgn>dpkg-deb/</prgn>
8522 This is so that the control file which is produced has
8523 the right permissions
8529 <prgn>dpkg-gencontrol</prgn> must be called after all the
8530 files which are to go into the package have been placed in
8531 the temporary build directory, so that its calculation of
8532 the installed size of a package is correct.
8536 It is also necessary for <prgn>dpkg-gencontrol</prgn> to
8537 be run after <prgn>dpkg-shlibdeps</prgn> so that the
8538 variable substitutions created by
8539 <prgn>dpkg-shlibdeps</prgn> in <file>debian/substvars</file>
8544 For a package which generates only one binary package, and
8545 which builds it in <file>debian/tmp</file> relative to the top
8546 of the source package, it is usually sufficient to call
8547 <prgn>dpkg-gencontrol</prgn>.
8551 Sources which build several binaries will typically need
8554 dpkg-gencontrol -Pdebian/tmp-<var>pkg</var> -p<var>package</var>
8555 </example> The <tt>-P</tt> tells
8556 <prgn>dpkg-gencontrol</prgn> that the package is being
8557 built in a non-default directory, and the <tt>-p</tt>
8558 tells it which package's control file should be generated.
8562 <prgn>dpkg-gencontrol</prgn> also adds information to the
8563 list of files in <file>debian/files</file>, for the benefit of
8564 (for example) a future invocation of
8565 <prgn>dpkg-genchanges</prgn>.</p>
8570 <prgn>dpkg-shlibdeps</prgn> - calculates shared library
8575 This program is usually called from <file>debian/rules</file>
8576 just before <prgn>dpkg-gencontrol</prgn> (see <ref
8577 id="pkg-sourcetree">), in the top level of the source tree.
8581 Its arguments are executables.
8584 In a forthcoming dpkg version,
8585 <prgn>dpkg-shlibdeps</prgn> would be required to be
8586 called on shared libraries as well.
8589 They may be specified either in the locations in the
8590 source tree where they are created or in the locations
8591 in the temporary build tree where they are installed
8592 prior to binary package creation.
8594 </footnote> for which shared library dependencies should
8595 be included in the binary package's control file.
8599 If some of the found shared libraries should only
8600 warrant a <tt>Recommends</tt> or <tt>Suggests</tt>, or if
8601 some warrant a <tt>Pre-Depends</tt>, this can be achieved
8602 by using the <tt>-d<var>dependency-field</var></tt> option
8603 before those executable(s). (Each <tt>-d</tt> option
8604 takes effect until the next <tt>-d</tt>.)
8608 <prgn>dpkg-shlibdeps</prgn> does not directly cause the
8609 output control file to be modified. Instead by default it
8610 adds to the <file>debian/substvars</file> file variable
8611 settings like <tt>shlibs:Depends</tt>. These variable
8612 settings must be referenced in dependency fields in the
8613 appropriate per-binary-package sections of the source
8618 For example, the <prgn>procps</prgn> package generates two
8619 kinds of binaries, simple C binaries like <prgn>ps</prgn>
8620 which require a predependency and full-screen ncurses
8621 binaries like <prgn>top</prgn> which require only a
8622 recommendation. It can say in its <file>debian/rules</file>:
8624 dpkg-shlibdeps -dPre-Depends ps -dRecommends top
8626 and then in its main control file <file>debian/control</file>:
8630 Pre-Depends: ${shlibs:Pre-Depends}
8631 Recommends: ${shlibs:Recommends}
8637 Sources which produce several binary packages with
8638 different shared library dependency requirements can use
8639 the <tt>-p<var>varnameprefix</var></tt> option to override
8640 the default <tt>shlibs:</tt> prefix (one invocation of
8641 <prgn>dpkg-shlibdeps</prgn> per setting of this option).
8642 They can thus produce several sets of dependency
8643 variables, each of the form
8644 <tt><var>varnameprefix</var>:<var>dependencyfield</var></tt>,
8645 which can be referred to in the appropriate parts of the
8646 binary package control files.
8653 <prgn>dpkg-distaddfile</prgn> - adds a file to
8654 <file>debian/files</file>
8658 Some packages' uploads need to include files other than
8659 the source and binary package files.
8663 <prgn>dpkg-distaddfile</prgn> adds a file to the
8664 <file>debian/files</file> file so that it will be included in
8665 the <file>.changes</file> file when
8666 <prgn>dpkg-genchanges</prgn> is run.
8670 It is usually invoked from the <tt>binary</tt> target of
8671 <file>debian/rules</file>:
8673 dpkg-distaddfile <var>filename</var> <var>section</var> <var>priority</var>
8675 The <var>filename</var> is relative to the directory where
8676 <prgn>dpkg-genchanges</prgn> will expect to find it - this
8677 is usually the directory above the top level of the source
8678 tree. The <file>debian/rules</file> target should put the
8679 file there just before or just after calling
8680 <prgn>dpkg-distaddfile</prgn>.
8684 The <var>section</var> and <var>priority</var> are passed
8685 unchanged into the resulting <file>.changes</file> file. See
8686 <ref id="pkg-f-classification">.
8691 <sect1><heading><prgn>dpkg-genchanges</prgn> - generates a <file>.changes</file> upload
8696 This program is usually called by package-independent
8697 automatic building scripts such as
8698 <prgn>dpkg-buildpackage</prgn>, but it may also be called
8703 It is usually called in the top level of a built source
8704 tree, and when invoked with no arguments will print out a
8705 straightforward <file>.changes</file> file based on the
8706 information in the source package's changelog and control
8707 file and the binary and source packages which should have
8713 <sect1><heading><prgn>dpkg-parsechangelog</prgn> - produces parsed representation of
8718 This program is used internally by
8719 <prgn>dpkg-source</prgn> et al. It may also occasionally
8720 be useful in <file>debian/rules</file> and elsewhere. It
8721 parses a changelog, <file>debian/changelog</file> by default,
8722 and prints a control-file format representation of the
8723 information in it to standard output.
8727 <sect1 id="pkg-dpkgarch"><heading><prgn>dpkg-architecture</prgn> -
8728 information about the build and host system
8732 This program can be used manually, but is also invoked by
8733 <tt>dpkg-buildpackage</tt> or <file>debian/rules</file> to set
8734 to set environment or make variables which specify the build and
8735 host architecture for the package building process.
8740 <sect id="pkg-sourcetree"><heading>The Debianised source tree
8744 The source archive scheme described later is intended to
8745 allow a Debianised source tree with some associated control
8746 information to be reproduced and transported easily. The
8747 Debianised source tree is a version of the original program
8748 with certain files added for the benefit of the
8749 Debianisation process, and with any other changes required
8750 made to the rest of the source code and installation
8755 The extra files created for Debian are in the subdirectory
8756 <file>debian</file> of the top level of the Debianised source
8757 tree. They are described below.
8760 <sect1 id="pkg-debianrules"><heading><file>debian/rules</file> - the main building
8765 This file is an executable makefile, and contains the
8766 package-specific recipies for compiling the package and
8767 building binary package(s) out of the source.
8771 It must start with the line <tt>#!/usr/bin/make -f</tt>,
8772 so that it can be invoked by saying its name rather than
8773 invoking <prgn>make</prgn> explicitly.
8777 Since an interactive <file>debian/rules</file> script makes it
8778 impossible to autocompile that package and also makes it
8779 hard for other people to reproduce the same binary
8780 package, all <strong>required targets</strong> have to be
8781 non-interactive. At a minimul, required targets are the
8782 ones called by <prgn>dpkg-buildpackage</prgn>, namely,
8783 <em>clean</em>, <em>binary</em>, <em>binary-arch</em>, and
8784 <em>build</em>. It also follows that any target that these
8785 targets depend on must also be non-interactive.
8789 The targets which are required to be present are:
8791 <tag><tt>build</tt></tag>
8794 This should perform all non-interactive
8795 configuration and compilation of the package. If a
8796 package has an interactive pre-build configuration
8797 routine, the Debianised source package should be
8798 built after this has taken place, so that it can be
8799 built without rerunning the configuration.
8803 A package may also provide both of the targets
8804 <tt>build-arch</tt> and <tt>build-indep</tt>. The
8805 <tt>build-arch</tt> target, if provided, should
8806 perform all non-interactive configuration and
8807 compilation required for producing all
8808 architecture-dependant binary packages (those packages
8809 for which the body of the <tt>Architecture</tt> field
8810 in <tt>debian/control</tt> is not <tt>all</tt>).
8811 Similarly, the <tt>build-indep</tt> target, if
8812 provided, should perform all non-interactive
8813 configuration and compilation required for producing
8814 all architecture-independent binary packages (those
8815 packages for which the body of the
8816 <tt>Architecture</tt> field in <tt>debian/control</tt>
8817 is <tt>all</tt>). The <tt>build</tt> target should
8818 depend on those of the targets <tt>build-arch</tt> and
8819 <tt>build-indep</tt> that are provided in the rules
8824 If one or both of the targets <tt>build-arch</tt> and
8825 <tt>build-indep</tt> are not provided, then invoking
8826 <file>debian/rules</file> with one of the not-provided
8827 targets as arguments should produce a exit status code
8828 of 2. Usually this is provided automatically by make
8829 if the target is missing.
8833 For some packages, notably ones where the same
8834 source tree is compiled in different ways to produce
8835 two binary packages, the <tt>build</tt> target does
8836 not make much sense. For these packages it is good
8837 enough to provide two (or more) targets
8838 (<tt>build-a</tt> and <tt>build-b</tt> or whatever)
8839 for each of the ways of building the package, and a
8840 <tt>build</tt> target that does nothing. The
8841 <tt>binary</tt> target will have to build the
8842 package in each of the possible ways and make the
8843 binary package out of each.
8847 The targets <tt>build</tt>, <tt>build-arch</tt>
8848 and <tt>build-indep</tt> target must not do
8849 anything that might require root privilege.
8853 The <tt>build</tt> target may need to run
8854 <tt>clean</tt> first - see below.
8858 When a package has a configuration routine that takes
8859 a long time, or when the makefiles are poorly
8860 designed, or when <tt>build</tt> needs to run
8861 <tt>clean</tt> first, it is a good idea to <tt>touch
8862 build</tt> when the build process is complete. This
8863 will ensure that if <tt>debian/rules build</tt> is run
8864 again it will not rebuild the whole program.
8868 <tag><tt>binary</tt>, <tt>binary-arch</tt>,
8869 <tt>binary-indep</tt>
8873 The <tt>binary</tt> target should be all that is
8874 necessary for the user to build the binary
8875 package. All these targets are required to be
8876 non-interactive. It is split into two parts:
8877 <tt>binary-arch</tt> builds the packages' output
8878 files which are specific to a particular
8879 architecture, and <tt>binary-indep</tt> builds
8880 those which are not.
8884 <tt>binary</tt> should usually be a target with
8885 no commands which simply depends on
8886 <prgn>binary-arch</prgn> and
8887 <prgn>binary-indep</prgn>.
8891 Both <prgn>binary-*</prgn> targets should depend on
8892 the <tt>build</tt> target, above, so that the
8893 package is built if it has not been already. It
8894 should then create the relevant binary package(s),
8895 using <prgn>dpkg-gencontrol</prgn> to make their
8896 control files and <prgn>dpkg-deb</prgn> to build
8897 them and place them in the parent of the top level
8902 If one of the <prgn>binary-*</prgn> targets has
8903 nothing to do (this will be always be the case if
8904 the source generates only a single binary package,
8905 whether architecture-dependent or not) it
8906 <em>must</em> still exist, but should always
8911 <ref id="pkg-binarypkg"> describes how to construct
8916 The <tt>binary</tt> targets must be invoked as
8921 <tag><tt>clean</tt></tag>
8925 This should undo any effects that the
8926 <tt>build</tt> and <tt>binary</tt> targets
8927 may have had, except that it should leave alone any
8928 output files created in the parent directory by a
8929 run of <tt>binary</tt>. This target is required
8930 to be non-interactive.
8934 If a <tt>build</tt> file is touched at the end
8935 of the <tt>build</tt> target, as suggested
8936 above, it must be removed as the first thing that
8937 <tt>clean</tt> does, so that running
8938 <tt>build</tt> again after an interrupted
8939 <tt>clean</tt> doesn't think that everything is
8944 The <tt>clean</tt> target must be invoked as
8945 root if <tt>binary</tt> has been invoked since
8946 the last <tt>clean</tt>, or if
8947 <tt>build</tt> has been invoked as root (since
8948 <tt>build</tt> may create directories, for
8953 <tag><tt>get-orig-source</tt> (optional)</tag>
8957 This target fetches the most recent version of the
8958 original source package from a canonical archive
8959 site (via FTP or WWW, for example), does any
8960 necessary rearrangement to turn it into the original
8961 source tarfile format described below, and leaves it
8962 in the current directory.
8966 This target may be invoked in any directory, and
8967 should take care to clean up any temporary files it
8972 This target is optional, but providing it if
8973 possible is a good idea.
8979 The <tt>build</tt>, <tt>binary</tt> and
8980 <tt>clean</tt> targets must be invoked with a current
8981 directory of the package's top-level directory.
8986 Additional targets may exist in <file>debian/rules</file>,
8987 either as published or undocumented interfaces or for the
8988 package's internal use.
8992 The architecture we build on and build for is determined by make
8993 variables via dpkg-architecture (see <ref id="pkg-dpkgarch">). You can
8994 get the Debian architecture and the GNU style architecture
8995 specification string for the build machine as well as the host
8996 machine. Here is a list of supported make variables:
8997 <list compact="compact">
8999 <p><tt>DEB_*_ARCH</tt> (the Debian architecture)</p>
9002 <p><tt>DEB_*_GNU_TYPE</tt> (the GNU style architecture
9003 specification string)</p>
9006 <p><tt>DEB_*_GNU_CPU</tt> (the CPU part of DEB_*_GNU_TYPE)</p>
9009 <p><tt>DEB_*_GNU_SYSTEM</tt> (the System part of
9015 where <tt>*</tt> is either <tt>BUILD</tt> for specification of
9016 the build machine or <tt>HOST</tt> for specification of the machine
9021 Backward compatibility can be provided in the rules file
9022 by setting the needed variables to suitable default
9023 values, please refer to the documentation of
9024 dpkg-architecture for details.
9028 It is important to understand that the <tt>DEB_*_ARCH</tt>
9029 string does only determine which Debian architecture we
9030 build on resp. for. It should not be used to get the CPU
9031 or System information, the GNU style variables should be
9037 <sect1><heading><file>debian/control</file>
9041 This file contains version-independent details about the
9042 source package and about the binary packages it creates.
9046 It is a series of sets of control fields, each
9047 syntactically similar to a binary package control file.
9048 The sets are separated by one or more blank lines. The
9049 first set is information about the source package in
9050 general; each subsequent set describes one binary package
9051 that the source tree builds.
9055 The syntax and semantics of the fields are described below
9056 in <ref id="pkg-controlfields">.
9060 The general (binary-package-independent) fields are:
9061 <list compact="compact">
9063 <p><qref id="pkg-f-Source"><tt>Source</tt></qref> (mandatory)</p>
9066 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
9070 <qref id="pkg-f-classification"><tt>Section</tt> and
9071 <tt>Priority</tt></qref>
9072 (classification, mandatory)
9077 <qref id="relationships"><tt>Build-Depends</tt> et
9078 al.</qref> (source package interrelationships)
9083 <qref id="pkg-f-Standards-Version"><tt>Standards-Version</tt></qref>
9089 The per-binary-package fields are:
9090 <list compact="compact">
9092 <p><qref id="pkg-f-Package"><tt>Package</tt></qref> (mandatory)</p>
9096 <qref id="pkg-f-Architecture"><tt>Architecture</tt></qref>
9100 <p><qref id="descriptions"><tt>Description</tt></qref></p>
9104 <qref id="pkg-f-classification"><tt>Section</tt> and
9105 <tt>Priority</tt></qref> (classification)</p>
9108 <p><qref id="pkg-f-Essential"><tt>Essential</tt></qref></p>
9112 <qref id="relationships"><tt>Depends</tt> et
9113 al.</qref> (binary package interrelationships)
9119 These fields are used by <prgn>dpkg-gencontrol</prgn> to
9120 generate control files for binary packages (see below), by
9121 <prgn>dpkg-genchanges</prgn> to generate the
9122 <tt>.changes</tt> file to accompany the upload, and by
9123 <prgn>dpkg-source</prgn> when it creates the <file>.dsc</file>
9124 source control file as part of a source archive.
9128 The fields here may contain variable references - their
9129 values will be substituted by
9130 <prgn>dpkg-gencontrol</prgn>, <prgn>dpkg-genchanges</prgn>
9131 or <prgn>dpkg-source</prgn> when they generate output
9132 control files. See <ref id="pkg-srcsubstvars"> for details.
9135 <p> <sect2><heading>User-defined fields
9139 Additional user-defined fields may be added to the
9140 source package control file. Such fields will be
9141 ignored, and not copied to (for example) binary or
9142 source package control files or upload control files.
9146 If you wish to add additional unsupported fields to
9147 these output files you should use the mechanism
9152 Fields in the main source control information file with
9153 names starting <tt>X</tt>, followed by one or more of
9154 the letters <tt>BCS</tt> and a hyphen <tt>-</tt>, will
9155 be copied to the output files. Only the part of the
9156 field name after the hyphen will be used in the output
9157 file. Where the letter <tt>B</tt> is used the field
9158 will appear in binary package control files, where the
9159 letter <tt>S</tt> is used in source package control
9160 files and where <tt>C</tt> is used in upload control
9161 (<tt>.changes</tt>) files.
9165 For example, if the main source information control file
9168 XBS-Comment: I stand between the candle and the star.
9170 then the binary and source package control files will contain the
9173 Comment: I stand between the candle and the star.
9180 <sect1 id="pkg-dpkgchangelog"><heading><file>debian/changelog</file>
9184 This file records the changes to the Debian-specific parts of the
9188 Though there is nothing stopping an author who is also
9189 the Debian maintainer from using it for all their
9190 changes, it will have to be renamed if the Debian and
9191 upstream maintainers become different
9198 It has a special format which allows the package building
9199 tools to discover which version of the package is being
9200 built and find out other release-specific information.
9204 That format is a series of entries like this:
9206 <var>package</var> (<var>version</var>) <var>distribution(s)</var>; urgency=<var>urgency</var>
9208 * <var>change details</var>
9209 <var>more change details</var>
9210 * <var>even more change details</var>
9212 -- <var>maintainer name and email address</var> <var>date</var>
9217 <var>package</var> and <var>version</var> are the source
9218 package name and version number.
9222 <var>distribution(s)</var> lists the distributions where
9223 this version should be installed when it is uploaded - it
9224 is copied to the <tt>Distribution</tt> field in the
9225 <tt>.changes</tt> file. See <ref id="pkg-f-Distribution">.
9229 <var>urgency</var> is the value for the <tt>Urgency</tt>
9230 field in the <file>.changes</file> file for the upload. See
9231 <ref id="pkg-f-Urgency">. It is not possible to specify an
9232 urgency containing commas; commas are used to separate
9233 <tt><var>keyword</var>=<var>value</var></tt> settings in
9234 the <prgn>dpkg</prgn> changelog format (though there is
9235 currently only one useful <var>keyword</var>,
9240 The change details may in fact be any series of lines
9241 starting with at least two spaces, but conventionally each
9242 change starts with an asterisk and a separating space and
9243 continuation lines are indented so as to bring them in
9244 line with the start of the text above. Blank lines may be
9245 used here to separate groups of changes, if desired.
9249 The maintainer name and email address should <em>not</em>
9250 necessarily be those of the usual package maintainer.
9251 They should be the details of the person doing
9252 <em>this</em> version. The information here will be
9253 copied to the <file>.changes</file> file, and then later used
9254 to send an acknowledgement when the upload has been
9259 The <var>date</var> should be in RFC822 format
9262 This is generated by the <prgn>822-date</prgn>
9265 </footnote>; it should include the timezone specified
9266 numerically, with the timezone name or abbreviation
9267 optionally present as a comment.
9271 The first "title" line with the package name should start
9272 at the left hand margin; the "trailer" line with the
9273 maintainer and date details should be preceded by exactly
9274 one space. The maintainer details and the date must be
9275 separated by exactly two spaces.
9279 An Emacs mode for editing this format is available: it is
9280 called <tt>debian-changelog-mode</tt>. You can have this
9281 mode selected automatically when you edit a Debian
9282 changelog by adding a local variables clause to the end of
9286 <sect2><heading>Defining alternative changelog formats
9290 It is possible to use a different format to the standard
9291 one, by providing a parser for the format you wish to
9296 In order to have <tt>dpkg-parsechangelog</tt> run your
9297 parser, you must include a line within the last 40 lines
9298 of your file matching the Perl regular expression:
9299 <tt>\schangelog-format:\s+([0-9a-z]+)\W</tt> The part in
9300 parentheses should be the name of the format. For
9301 example, you might say:
9303 @@@ changelog-format: joebloggs @@@
9305 Changelog format names are non-empty strings of alphanumerics.
9309 If such a line exists then <tt>dpkg-parsechangelog</tt>
9310 will look for the parser as
9311 <file>/usr/lib/dpkg/parsechangelog/<var>format-name</var></file>
9313 <file>/usr/local/lib/dpkg/parsechangelog/<var>format-name</var></file>;
9314 it is an error for it not to find it, or for it not to
9315 be an executable program. The default changelog format
9316 is <tt>dpkg</tt>, and a parser for it is provided with
9317 the <tt>dpkg</tt> package.
9321 The parser will be invoked with the changelog open on
9322 standard input at the start of the file. It should read
9323 the file (it may seek if it wishes) to determine the
9324 information required and return the parsed information
9325 to standard output in the form of a series of control
9326 fields in the standard format. By default it should
9327 return information about only the most recent version in
9328 the changelog; it should accept a
9329 <tt>-v<var>version</var></tt> option to return changes
9330 information from all versions present <em>strictly
9331 after</em> <var>version</var>, and it should then be an
9332 error for <var>version</var> not to be present in the
9338 <list compact="compact">
9340 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
9343 <p><qref id="versions"><tt>Version</tt></qref> (mandatory)</p>
9347 <qref id="pkg-f-Distribution"><tt>Distribution</tt></qref>
9352 <p><qref id="pkg-f-Urgency"><tt>Urgency</tt></qref> (mandatory)</p>
9356 <qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref>
9361 <p><qref id="pkg-f-Date"><tt>Date</tt></qref></p>
9365 <qref id="pkg-f-Changes"><tt>Changes</tt></qref>
9372 If several versions are being returned (due to the use
9373 of <tt>-v</tt>), the urgency value should be of the
9374 highest urgency code listed at the start of any of the
9375 versions requested followed by the concatenated
9376 (space-separated) comments from all the versions
9377 requested; the maintainer, version, distribution and
9378 date should always be from the most recent version.
9382 For the format of the <tt>Changes</tt> field see <ref
9383 id="pkg-f-Changes">.
9387 If the changelog format which is being parsed always or
9388 almost always leaves a blank line between individual
9389 change notes these blank lines should be stripped out,
9390 so as to make the resulting output compact.
9394 If the changelog format does not contain date or package
9395 name information this information should be omitted from
9396 the output. The parser should not attempt to synthesise
9397 it or find it from other sources.
9401 If the changelog does not have the expected format the
9402 parser should exit with a nonzero exit status, rather
9403 than trying to muddle through and possibly generating
9408 A changelog parser may not interact with the user at
9412 <!-- FIXME: section pkg-srcsubstvars is the same as srcsubstvars -->
9414 <sect1 id="pkg-srcsubstvars"><heading><file>debian/substvars</file>
9415 and variable substitutions
9419 When <prgn>dpkg-gencontrol</prgn>,
9420 <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
9421 generate control files they do variable substitutions on
9422 their output just before writing it. Variable
9423 substitutions have the form
9424 <tt>${<var>variable-name</var>}</tt>. The optional file
9425 <file>debian/substvars</file> contains variable substitutions
9426 to be used; variables can also be set directly from
9427 <file>debian/rules</file> using the <tt>-V</tt> option to the
9428 source packaging commands, and certain predefined
9429 variables are available.
9433 This file is usually generated and modified dynamically by
9434 <file>debian/rules</file> targets, in which case it must be
9435 removed by the <tt>clean</tt> target.
9439 See <manref name="dpkg-source" section="1"> for full
9440 details about source variable substitutions, including the
9441 format of <file>debian/substvars</file>.</p>
9444 <sect1><heading><file>debian/files</file>
9448 This file is not a permanent part of the source tree; it
9449 is used while building packages to record which files are
9450 being generated. <prgn>dpkg-genchanges</prgn> uses it
9451 when it generates a <file>.changes</file> file.
9455 It should not exist in a shipped source package, and so it
9456 (and any backup files or temporary files such as
9457 <file>files.new</file>
9460 <file>files.new</file> is used as a temporary file by
9461 <prgn>dpkg-gencontrol</prgn> and
9462 <prgn>dpkg-distaddfile</prgn> - they write a new
9463 version of <file>files</file> here before renaming it,
9464 to avoid leaving a corrupted copy if an error
9467 </footnote>) should be removed by the
9468 <tt>clean</tt> target. It may also be wise to
9469 ensure a fresh start by emptying or removing it at the
9470 start of the <tt>binary</tt> target.
9474 <prgn>dpkg-gencontrol</prgn> adds an entry to this file
9475 for the <file>.deb</file> file that will be created by
9476 <prgn>dpkg-deb</prgn> from the control file that it
9477 generates, so for most packages all that needs to be done
9478 with this file is to delete it in <tt>clean</tt>.
9482 If a package upload includes files besides the source
9483 package and any binary packages whose control files were
9484 made with <prgn>dpkg-gencontrol</prgn> then they should be
9485 placed in the parent of the package's top-level directory
9486 and <prgn>dpkg-distaddfile</prgn> should be called to add
9487 the file to the list in <file>debian/files</file>.</p>
9490 <sect1><heading><file>debian/tmp</file>
9494 This is the canonical temporary location for the
9495 construction of binary packages by the <tt>binary</tt>
9496 target. The directory <file>tmp</file> serves as the root of
9497 the filesystem tree as it is being constructed (for
9498 example, by using the package's upstream makefiles install
9499 targets and redirecting the output there), and it also
9500 contains the <tt>DEBIAN</tt> subdirectory. See <ref
9501 id="pkg-bincreating">.
9505 If several binary packages are generated from the same
9506 source tree it is usual to use several
9507 <file>debian/tmp<var>something</var></file> directories, for
9508 example <file>tmp-a</file> or <file>tmp-doc</file>.
9512 Whatever <file>tmp</file> directories are created and used by
9513 <tt>binary</tt> must of course be removed by the
9514 <tt>clean</tt> target.</p></sect1>
9518 <sect id="pkg-sourcearchives"><heading>Source packages as archives
9522 As it exists on the FTP site, a Debian source package
9523 consists of three related files. You must have the right
9524 versions of all three to be able to use them.
9529 <tag>Debian source control file - <tt>.dsc</tt></tag>
9533 This file contains a series of fields, identified and
9534 separated just like the fields in the control file of
9535 a binary package. The fields are listed below; their
9536 syntax is described above, in <ref id="pkg-controlfields">.
9537 <list compact="compact">
9539 <p><qref id="pkg-f-Source"><tt>Source</tt></qref></p>
9542 <p><qref id="versions"><tt>Version</tt></qref></p>
9545 <p><qref id="pkg-f-Maintainer"><tt>Maintainer</tt></qref></p>
9548 <p><qref id="pkg-f-Binary"><tt>Binary</tt></qref></p>
9551 <p><qref id="pkg-f-Architecture"><tt>Architecture</tt></qref></p>
9555 <qref id="relationships"><tt>Build-Depends</tt> et
9556 al.</qref> (source package interrelationships)
9561 <qref id="pkg-f-Standards-Version"><tt>Standards-Version</tt></qref></p>
9564 <p><qref id="pkg-f-Files"><tt>Files</tt></qref></p>
9569 The source package control file is generated by
9570 <prgn>dpkg-source</prgn> when it builds the source
9571 archive, from other files in the source package,
9572 described above. When unpacking it is checked against
9573 the files and directories in the other parts of the
9574 source package, as described below.</p>
9578 Original source archive -
9580 <var>package</var>_<var>upstream-version</var>.orig.tar.gz
9587 This is a compressed (with <tt>gzip -9</tt>)
9588 <prgn>tar</prgn> file containing the source code from
9589 the upstream authors of the program. The tarfile
9590 unpacks into a directory
9591 <file><var>package</var>-<var>upstream-version</var>.orig</file>,
9592 and does not contain files anywhere other than in
9593 there or in its subdirectories.</p>
9597 Debianisation diff -
9599 <var>package</var>_<var>upstream_version-revision</var>.diff.gz
9605 This is a unified context diff (<tt>diff -u</tt>)
9606 giving the changes which are required to turn the
9607 original source into the Debian source. These changes
9608 may only include editing and creating plain files.
9609 The permissions of files, the targets of symbolic
9610 links and the characteristics of special files or
9611 pipes may not be changed and no files may be removed
9616 All the directories in the diff must exist, except the
9617 <file>debian</file> subdirectory of the top of the source
9618 tree, which will be created by
9619 <prgn>dpkg-source</prgn> if necessary when unpacking.
9623 The <prgn>dpkg-source</prgn> program will
9624 automatically make the <file>debian/rules</file> file
9625 executable (see below).</p></item>
9630 If there is no original source code - for example, if the
9631 package is specially prepared for Debian or the Debian
9632 maintainer is the same as the upstream maintainer - the
9633 format is slightly different: then there is no diff, and the
9635 <file><var>package</var>_<var>version</var>.tar.gz</file> and
9636 contains a directory
9637 <file><var>package</var>-<var>version</var></file>.
9641 <sect><heading>Unpacking a Debian source package without
9642 <prgn>dpkg-source</prgn>
9646 <tt>dpkg-source -x</tt> is the recommended way to unpack a
9647 Debian source package. However, if it is not available it
9648 is possible to unpack a Debian source archive as follows:
9649 <enumlist compact="compact">
9652 Untar the tarfile, which will create a <file>.orig</file>
9656 <p>Rename the <file>.orig</file> directory to
9657 <file><var>package</var>-<var>version</var></file>.</p>
9661 Create the subdirectory <file>debian</file> at the top of
9662 the source tree.</p>
9664 <item><p>Apply the diff using <tt>patch -p0</tt>.</p>
9666 <item><p>Untar the tarfile again if you want a copy of the original
9667 source code alongside the Debianised version.</p>
9672 It is not possible to generate a valid Debian source archive
9673 without using <prgn>dpkg-source</prgn>. In particular,
9674 attempting to use <prgn>diff</prgn> directly to generate the
9675 <file>.diff.gz</file> file will not work.
9678 <sect1><heading>Restrictions on objects in source packages
9682 The source package may not contain any hard links
9685 This is not currently detected when building source
9686 packages, but only when extracting
9692 Hard links may be permitted at some point in the
9693 future, but would require a fair amount of
9696 </footnote>, device special files, sockets or setuid or
9700 Setgid directories are allowed.
9706 The source packaging tools manage the changes between the
9707 original and Debianised source using <prgn>diff</prgn> and
9708 <prgn>patch</prgn>. Turning the original source tree as
9709 included in the <file>.orig.tar.gz</file> into the debianised
9710 source must not involve any changes which cannot be
9711 handled by these tools. Problematic changes which cause
9712 <prgn>dpkg-source</prgn> to halt with an error when
9713 building the source package are:
9714 <list compact="compact">
9715 <item><p>Adding or removing symbolic links, sockets or pipes.</p>
9717 <item><p>Changing the targets of symbolic links.</p>
9719 <item><p>Creating directories, other than <file>debian</file>.</p>
9721 <item><p>Changes to the contents of binary files.</p></item>
9722 </list> Changes which cause <prgn>dpkg-source</prgn> to
9723 print a warning but continue anyway are:
9724 <list compact="compact">
9727 Removing files, directories or symlinks.
9730 Renaming a file is not treated specially - it is
9731 seen as the removal of the old file (which
9732 generates a warning, but is otherwise ignored),
9733 and the creation of the new
9740 Changed text files which are missing the usual final
9741 newline (either in the original or the modified
9746 Changes which are not represented, but which are not detected by
9747 <prgn>dpkg-source</prgn>, are:
9748 <list compact="compact">
9749 <item><p>Changing the permissions of files (other than
9750 <file>debian/rules</file>) and directories.</p></item>
9755 The <file>debian</file> directory and <file>debian/rules</file>
9756 are handled specially by <prgn>dpkg-source</prgn> - before
9757 applying the changes it will create the <file>debian</file>
9758 directory, and afterwards it will make
9759 <file>debian/rules</file> world-exectuable.
9765 <appendix id="pkg-controlfields"><heading>Control files and their
9766 fields (from old Packaging Manual)
9770 Many of the tools in the <prgn>dpkg</prgn> suite manipulate
9771 data in a common format, known as control files. Binary and
9772 source packages have control data as do the <file>.changes</file>
9773 files which control the installation of uploaded files, and
9774 <prgn>dpkg</prgn>'s internal databases are in a similar
9778 <sect><heading>Syntax of control files
9782 A file consists of one or more paragraphs of fields. The
9783 paragraphs are separated by blank lines. Some control files
9784 only allow one paragraph; others allow several, in which
9785 case each paragraph often refers to a different package.
9789 Each paragraph is a series of fields and values; each field
9790 consists of a name, followed by a colon and the value. It
9791 ends at the end of the line. Horizontal whitespace (spaces
9792 and tabs) may occur before or after the value and is ignored
9793 there; it is conventional to put a single space after the
9798 Some fields' values may span several lines; in this case
9799 each continuation line <em>must</em> start with a space or
9800 tab. Any trailing spaces or tabs at the end of individual
9801 lines of a field value are ignored.
9805 Except where otherwise stated only a single line of data is
9806 allowed and whitespace is not significant in a field body.
9807 Whitespace may never appear inside names (of packages,
9808 architectures, files or anything else), version numbers or
9809 in between the characters of multi-character version
9814 Field names are not case-sensitive, but it is usual to
9815 capitalise the field names using mixed case as shown below.
9819 Blank lines, or lines consisting only of spaces and tabs,
9820 are not allowed within field values or between fields - that
9821 would mean a new paragraph.
9825 It is important to note that there are several fields which
9826 are optional as far as <prgn>dpkg</prgn> and the related
9827 tools are concerned, but which must appear in every Debian
9828 package, or whose omission may cause problems.
9832 <sect><heading>List of fields
9835 <sect1 id="pkg-f-Package"><heading><tt>Package</tt>
9839 The name of the binary package. Package names consist of
9840 the alphanumerics and <tt>+</tt> <tt>-</tt> <tt>.</tt>
9841 (plus, minus and full stop).
9844 The characters <tt>@</tt> <tt>:</tt> <tt>=</tt>
9845 <tt>%</tt> <tt>_</tt> (at, colon, equals, percent
9846 and underscore) used to be legal and are still
9847 accepted when found in a package file, but may not be
9848 used in new packages
9854 They must be at least two characters and must start with
9855 an alphanumeric. In current versions of dpkg they are
9856 sort of case-sensitive<footnote><p>This is a
9857 bug.</p></footnote>; use lowercase package names unless
9858 the package you're building (or referring to, in other
9859 fields) is already using uppercase.</p>
9862 <sect1 id="pkg-f-Version"><heading><tt>Version</tt>
9866 This lists the source or binary package's version number -
9867 see <ref id="versions">.
9872 <sect1 id="pkg-f-Architecture"><heading><tt>Architecture</tt>
9876 This is the architecture string; it is a single word for
9877 the Debian architecture.
9881 <prgn>dpkg</prgn> will check the declared architecture of
9882 a binary package against its own compiled-in value before
9887 The special value <tt>all</tt> indicates that the package
9888 is architecture-independent.
9892 In the main <file>debian/control</file> file in the source
9893 package, or in the source package control file
9894 <file>.dsc</file>, a list of architectures (separated by
9895 spaces) is also allowed, as is the special value
9896 <tt>any</tt>. A list indicates that the source will build
9897 an architecture-dependent package, and will only work
9898 correctly on the listed architectures. <tt>any</tt>
9899 indicates that though the source package isn't dependent
9900 on any particular architecture and should compile fine on
9901 any one, the binary package(s) produced are not
9902 architecture-independent but will instead be specific to
9903 whatever the current build architecture is.
9907 In a <file>.changes</file> file the <tt>Architecture</tt>
9908 field lists the architecture(s) of the package(s)
9909 currently being uploaded. This will be a list; if the
9910 source for the package is being uploaded too the special
9911 entry <tt>source</tt> is also present.
9915 See <ref id="pkg-debianrules"> for information how to get the
9916 architecture for the build process.
9920 <sect1 id="pkg-f-Maintainer"><heading><tt>Maintainer</tt>
9924 The package maintainer's name and email address. The name
9925 should come first, then the email address inside angle
9926 brackets <tt><></tt> (in RFC822 format).
9930 If the maintainer's name contains a full stop then the
9931 whole field will not work directly as an email address due
9932 to a misfeature in the syntax specified in RFC822; a
9933 program using this field as an address must check for this
9934 and correct the problem if necessary (for example by
9935 putting the name in round brackets and moving it to the
9936 end, and bringing the email address forward).
9940 In a <file>.changes</file> file or parsed changelog data this
9941 contains the name and email address of the person
9942 responsible for the particular version in question - this
9943 may not be the package's usual maintainer.
9947 This field is usually optional in as far as the
9948 <prgn>dpkg</prgn> are concerned, but its absence when
9949 building packages usually generates a warning.</p>
9952 <sect1 id="pkg-f-Source"><heading><tt>Source</tt>
9956 This field identifies the source package name.
9960 In a main source control information or a
9961 <file>.changes</file> or <file>.dsc</file> file or parsed
9962 changelog data this may contain only the name of the
9967 In the control file of a binary package (or in a
9968 <file>Packages</file> file) it may be followed by a version
9969 number in parentheses.
9972 It is usual to leave a space after the package name if
9973 a version number is specified.
9975 </footnote> This version number may be omitted (and is, by
9976 <prgn>dpkg-gencontrol</prgn>) if it has the same value as
9977 the <tt>Version</tt> field of the binary package in
9978 question. The field itself may be omitted from a binary
9979 package control file when the source package has the same
9980 name and version as the binary package.
9984 <sect1><heading>Package interrelationship fields:
9985 <tt>Depends</tt>, <tt>Pre-Depends</tt>,
9986 <tt>Recommends</tt> <tt>Suggests</tt>, <tt>Conflicts</tt>,
9987 <tt>Provides</tt>, <tt>Replaces</tt>
9991 These fields describe the package's relationships with
9992 other packages. Their syntax and semantics are described
9993 in <ref id="relationships">.</p>
9996 <sect1 id="pkg-f-Description"><heading><tt>Description</tt>
10000 In a binary package <tt>Packages</tt> file or main source
10001 control file this field contains a description of the
10002 binary package, in a special format. See <ref
10003 id="descriptions"> for details.
10007 In a <file>.changes</file> file it contains a summary of the
10008 descriptions for the packages being uploaded. The part of
10009 the field before the first newline is empty; thereafter
10010 each line has the name of a binary package and the summary
10011 description line from that binary package. Each line is
10012 indented by one space.</p>
10015 <sect1 id="pkg-f-Essential"><heading><tt>Essential</tt>
10019 This is a boolean field which may occur only in the
10020 control file of a binary package (or in the
10021 <file>Packages</file> file) or in a per-package fields
10022 paragraph of a main source control data file.
10026 If set to <tt>yes</tt> then <prgn>dpkg</prgn> and
10027 <prgn>dselect</prgn> will refuse to remove the package
10028 (though it can be upgraded and/or replaced). The other
10029 possible value is <tt>no</tt>, which is the same as not
10030 having the field at all.</p>
10033 <sect1 id="pkg-f-classification"><heading><tt>Section</tt> and
10038 These two fields classify the package. The
10039 <tt>Priority</tt> represents how important that it is that
10040 the user have it installed; the <tt>Section</tt>
10041 represents an application area into which the package has
10046 When they appear in the <file>debian/control</file> file these
10047 fields give values for the section and priority subfields
10048 of the <tt>Files</tt> field of the <file>.changes</file> file,
10049 and give defaults for the section and priority of the
10054 The section and priority are represented, though not as
10055 separate fields, in the information for each file in the
10056 <qref id="pkg-f-Files"><tt>-File</tt></qref>field of a
10057 <file>.changes</file> file. The section value in a
10058 <file>.changes</file> file is used to decide where to install
10059 a package in the FTP archive.
10063 These fields are not used by by <prgn>dpkg</prgn> proper,
10064 but by <prgn>dselect</prgn> when it sorts packages and
10069 These fields can appear in binary package control files,
10070 in which case they provide a default value in case the
10071 <file>Packages</file> files are missing the information.
10072 <prgn>dpkg</prgn> and <prgn>dselect</prgn> will only use
10073 the value from a <file>.deb</file> file if they have no other
10074 information; a value listed in a <file>Packages</file> file
10075 will always take precedence. By default
10076 <prgn>dpkg-gencontrol</prgn> does not include the section
10077 and priority in the control file of a binary package - use
10078 the <tt>-isp</tt>, <tt>-is</tt> or <tt>-ip</tt> options to
10079 achieve this effect.</p>
10082 <sect1 id="pkg-f-Binary"><heading><tt>Binary</tt>
10086 This field is a list of binary packages.
10090 When it appears in the <file>.dsc</file> file it is the list
10091 of binary packages which a source package can produce. It
10092 does not necessarily produce all of these binary packages
10093 for every architecture. The source control file doesn't
10094 contain details of which architectures are appropriate for
10095 which of the binary packages.
10099 When it appears in a <file>.changes</file> file it lists the
10100 names of the binary packages actually being uploaded.
10104 The syntax is a list of binary packages separated by
10108 A space after each comma is conventional.
10110 </footnote> Currently the packages must be separated using
10111 only spaces in the <file>.changes</file> file.</p>
10114 <sect1 id="pkg-f-Installed-Size"><heading><tt>Installed-Size</tt>
10118 This field appears in the control files of binary
10119 packages, and in the <file>Packages</file> files. It gives
10120 the total amount of disk space required to install the
10125 The disk space is represented in kilobytes as a simple
10126 decimal number.</p>
10129 <sect1 id="pkg-f-Files"><heading><tt>Files</tt>
10133 This field contains a list of files with information about
10134 each one. The exact information and syntax varies with
10135 the context. In all cases the part of the field
10136 contents on the same line as the field name is empty. The
10137 remainder of the field is one line per file, each line
10138 being indented by one space and containing a number of
10139 sub-fields separated by spaces.
10143 In the <file>.dsc</file> (Debian source control) file each
10144 line contains the MD5 checksum, size and filename of the
10145 tarfile and (if applicable) diff file which make up the
10146 remainder of the source package.
10149 That is, the parts which are not the
10152 </footnote> The exact forms of the filenames are described
10153 in <ref id="pkg-sourcearchives">.
10157 In the <file>.changes</file> file this contains one line per
10158 file being uploaded. Each line contains the MD5 checksum,
10159 size, section and priority and the filename. The section
10160 and priority are the values of the corresponding fields in
10161 the main source control file - see <ref
10162 id="pkg-f-classification">. If no section or priority is
10163 specified then <tt>-</tt> should be used, though section
10164 and priority values must be specified for new packages to
10165 be installed properly.
10169 The special value <tt>byhand</tt> for the section in a
10170 <tt>.changes</tt> file indicates that the file in question
10171 is not an ordinary package file and must by installed by
10172 hand by the distribution maintainers. If the section is
10173 <tt>byhand</tt> the priority should be <tt>-</tt>.
10177 If a new Debian revision of a package is being shipped and
10178 no new original source archive is being distributed the
10179 <tt>.dsc</tt> must still contain the <tt>Files</tt> field
10180 entry for the original source archive
10181 <file><var>package</var>-<var>upstream-version</var>.orig.tar.gz</file>,
10182 but the <file>.changes</file> file should leave it out. In
10183 this case the original source archive on the distribution
10184 site must match exactly, byte-for-byte, the original
10185 source archive which was used to generate the
10186 <file>.dsc</file> file and diff which are being uploaded.</p>
10191 id="pkg-f-Standards-Version"><heading><tt>Standards-Version</tt>
10195 The most recent version of the standards (the Debian Policy
10196 and associated texts) with which the package complies. This
10197 is updated manually when editing the source package to
10198 conform to newer standards; it can sometimes be used to
10199 tell when a package needs attention.
10203 Its format is the same as that of a version number except
10204 that no epoch or Debian revision is allowed - see <ref
10205 id="versions">.</p>
10209 <sect1 id="pkg-f-Distribution"><heading><tt>Distribution</tt>
10213 In a <file>.changes</file> file or parsed changelog output
10214 this contains the (space-separated) name(s) of the
10215 distribution(s) where this version of the package should
10216 be or was installed. Distribution names follow the rules
10217 for package names. (See <ref id="pkg-f-Package">).
10221 Current distribution values are:
10223 <tag><em>stable</em></tag>
10226 This is the current "released" version of Debian
10227 GNU/Linux. A new version is released approximately
10228 every 3 months after the <em>development</em> code has
10229 been <em>frozen</em> for a month of testing. Once the
10230 distribution is <em>stable</em> only major bug fixes
10231 are allowed. When changes are made to this
10232 distribution, the release number is increased
10233 (for example: 1.2r1 becomes 1.2r2 then 1.2r3, etc).
10237 <tag><em>unstable</em></tag>
10240 This distribution value refers to the
10241 <em>developmental</em> part of the Debian distribution
10242 tree. New packages, new upstream versions of packages
10243 and bug fixes go into the <em>unstable</em> directory
10244 tree. Download from this distribution at your own
10248 <tag><em>contrib</em></tag>
10251 The packages with this distribution value do not meet
10252 the criteria for inclusion in the main Debian
10253 distribution as defined by the Policy Manual, but meet
10254 the criteria for the <em>contrib</em>
10255 Distribution. There is currently no distinction
10256 between stable and unstable packages in the
10257 <em>contrib</em> or <em>non-free</em>
10258 distributions. Use your best judgement in downloading
10259 from this Distribution.</p>
10262 <tag><em>non-free</em></tag>
10265 Like the packages in the <em>contrib</em> seciton,
10266 the packages in <em>non-free</em> do not meet the
10267 criteria for inclusion in the main Debian distribution
10268 as defined by the Policy Manual. Again, use your best
10269 judgement in downloading from this Distribution.</p>
10271 <tag><em>experimental</em></tag>
10274 The packages with this distribution value are deemed
10275 by their maintainers to be high risk. Oftentimes they
10276 represent early beta or developmental packages from
10277 various sources that the maintainers want people to
10278 try, but are not ready to be a part of the other parts
10279 of the Debian distribution tree. Download at your own
10283 <tag><em>frozen</em></tag>
10286 From time to time, (currently, every 3 months) the
10287 <em>unstable</em> distribution enters a state of
10288 "code-freeze" in anticipation of release as a
10289 <em>stable</em> version. During this period of testing
10290 (usually 4 weeks) only fixes for existing or
10291 newly-discovered bugs will be allowed.
10294 </taglist> You should list <em>all</em> distributions that
10295 the package should be installed into. Except in unusual
10296 circumstances, installations to <em>stable</em> should also
10297 go into <em>frozen</em> (if it exists) and
10298 <em>unstable</em>. Likewise, installations into
10299 <em>frozen</em> should also go into <em>unstable</em>.</p>
10302 <sect1 id="pkg-f-Urgency"><heading><tt>Urgency</tt>
10306 This is a description of how important it is to upgrade to
10307 this version from previous ones. It consists of a single
10308 keyword usually taking one of the values <tt>LOW</tt>,
10309 <tt>MEDIUM</tt> or <tt>HIGH</tt>) followed by an optional
10310 commentary (separated by a space) which is usually in
10311 parentheses. For example:
10313 Urgency: LOW (HIGH for diversions users)
10318 This field appears in the <file>.changes</file> file and in
10319 parsed changelogs; its value appears as the value of the
10320 <tt>urgency</tt> attribute in a <prgn>dpkg</prgn>-style
10321 changelog (see <ref id="pkg-dpkgchangelog">).
10325 Urgency keywords are not case-sensitive.</p>
10328 <sect1 id="pkg-f-Date"><heading><tt>Date</tt>
10332 In <tt>.changes</tt> files and parsed changelogs, this
10333 gives the date the package was built or last edited.</p>
10336 <sect1 id="pkg-f-Format"><heading><tt>Format</tt>
10340 This field occurs in <file>.changes</file> files, and
10341 specifies a format revision for the file. The format
10342 described here is version <tt>1.5</tt>. The syntax of the
10343 format value is the same as that of a package version
10344 number except that no epoch or Debian revision is allowed
10345 - see <ref id="versions">.</p>
10348 <sect1 id="pkg-f-Changes"><heading><tt>Changes</tt>
10352 In a <file>.changes</file> file or parsed changelog this field
10353 contains the human-readable changes data, describing the
10354 differences between the last version and the current one.
10358 There should be nothing in this field before the first
10359 newline; all the subsequent lines must be indented by at
10360 least one space; blank lines must be represented by a line
10361 consiting only of a space and a full stop.
10365 Each version's change information should be preceded by a
10366 "title" line giving at least the version, distribution(s)
10367 and urgency, in a human-readable way.
10371 If data from several versions is being returned the entry
10372 for the most recent version should be returned first, and
10373 entries should be separated by the representation of a
10374 blank line (the "title" line may also be followed by the
10375 representation of blank line).</p>
10378 <sect1 id="pkg-f-Filename"><heading><tt>Filename</tt> and
10379 <tt>MSDOS-Filename</tt>
10383 These fields in <tt>Packages</tt> files give the
10384 filename(s) of (the parts of) a package in the
10385 distribution directories, relative to the root of the
10386 Debian hierarchy. If the package has been split into
10387 several parts the parts are all listed in order, separated
10391 <sect1 id="pkg-f-Size"><heading><tt>Size</tt> and <tt>MD5sum</tt>
10395 These fields in <file>Packages</file> files give the size (in
10396 bytes, expressed in decimal) and MD5 checksum of the
10397 file(s) which make(s) up a binary package in the
10398 distribution. If the package is split into several parts
10399 the values for the parts are listed in order, separated by
10403 <sect1 id="pkg-f-Status"><heading><tt>Status</tt>
10407 This field in <prgn>dpkg</prgn>'s status file records
10408 whether the user wants a package installed, removed or
10409 left alone, whether it is broken (requiring
10410 reinstallation) or not and what its current state on the
10411 system is. Each of these pieces of information is a
10415 <sect1 id="pkg-f-Config-Version"><heading><tt>Config-Version</tt>
10419 If a package is not installed or not configured, this
10420 field in <prgn>dpkg</prgn>'s status file records the last
10421 version of the package which was successfully
10425 <sect1 id="pkg-f-Conffiles"><heading><tt>Conffiles</tt>
10429 This field in <prgn>dpkg</prgn>'s status file contains
10430 information about the automatically-managed configuration
10431 files held by a package. This field should <em>not</em>
10432 appear anywhere in a package!</p>
10435 <sect1><heading>Obsolete fields
10439 These are still recognised by <prgn>dpkg</prgn> but should
10440 not appear anywhere any more.
10441 <taglist compact="compact">
10443 <tag><tt>Revision</tt></tag>
10444 <tag><tt>Package-Revision</tt></tag>
10445 <tag><tt>Package_Revision</tt></tag>
10448 The Debian revision part of the package version was
10449 at one point in a separate control file field. This
10450 field went through several names.</p>
10453 <tag><tt>Recommended</tt></tag>
10454 <item><p>Old name for <tt>Recommends</tt></p>
10457 <tag><tt>Optional</tt></tag>
10458 <item><p>Old name for <tt>Suggests</tt>.</p>
10460 <tag><tt>Class</tt></tag>
10461 <item><p>Old name for <tt>Priority</tt>.</p>
10469 <appendix id="pkg-conffiles"><heading>Configuration file handling
10470 (from old Packaging Manual)
10474 <prgn>dpkg</prgn> can do a certain amount of automatic
10475 handling of package configuration files.
10479 Whether this mechanism is appropriate depends on a number of
10480 factors, but basically there are two approaches to any
10481 particular configuration file.
10485 The easy method is to ship a best-effort configuration in the
10486 package, and use <prgn>dpkg</prgn>'s conffile mechanism to
10487 handle updates. If the user is unlikely to want to edit the
10488 file, but you need them to be able to without losing their
10489 changes, and a new package with a changed version of the file
10490 is only released infrequently, this is a good approach.
10494 The hard method is to build the configuration file from
10495 scratch in the <prgn>postinst</prgn> script, and to take the
10496 responsibility for fixing any mistakes made in earlier
10497 versions of the package automatically. This will be
10498 appropriate if the file is likely to need to be different on
10502 <sect><heading>Automatic handling of configuration files by
10507 A package may contain a control area file called
10508 <tt>conffiles</tt>. This file should be a list of filenames
10509 of configuration files needing automatic handling, separated
10510 by newlines. The filenames should be absolute pathnames,
10511 and the files referred to should actually exist in the
10516 When a package is upgraded <prgn>dpkg</prgn> will process
10517 the configuration files during the configuration stage,
10518 shortly before it runs the package's <prgn>postinst</prgn>
10523 For each file it checks to see whether the version of the
10524 file included in the package is the same as the one that was
10525 included in the last version of the package (the one that is
10526 being upgraded from); it also compares the version currently
10527 installed on the system with the one shipped with the last
10532 If neither the user nor the package maintainer has changed
10533 the file, it is left alone. If one or the other has changed
10534 their version, then the changed version is preferred - i.e.,
10535 if the user edits their file, but the package maintainer
10536 doesn't ship a different version, the user's changes will
10537 stay, silently, but if the maintainer ships a new version
10538 and the user hasn't edited it the new version will be
10539 installed (with an informative message). If both have
10540 changed their version the user is prompted about the problem
10541 and must resolve the differences themselves.
10545 The comparisons are done by calculating the MD5 message
10546 digests of the files, and storing the MD5 of the file as it
10547 was included in the most recent version of the package.
10551 When a package is installed for the first time
10552 <prgn>dpkg</prgn> will install the file that comes with it,
10553 unless that would mean overwriting a file already on the
10558 However, note that <prgn>dpkg</prgn> will <em>not</em>
10559 replace a conffile that was removed by the user (or by a
10560 script). This is necessary because with some programs a
10561 missing file produces an effect hard or impossible to
10562 achieve in another way, so that a missing file needs to be
10563 kept that way if the user did it.
10567 Note that a package should <em>not</em> modify a
10568 <prgn>dpkg</prgn>-handled conffile in its maintainer
10569 scripts. Doing this will lead to <prgn>dpkg</prgn> giving
10570 the user confusing and possibly dangerous options for
10571 conffile update when the package is upgraded.</p>
10574 <sect><heading>Fully-featured maintainer script configuration
10579 For files which contain site-specific information such as
10580 the hostname and networking details and so forth, it is
10581 better to create the file in the package's
10582 <prgn>postinst</prgn> script.
10586 This will typically involve examining the state of the rest
10587 of the system to determine values and other information, and
10588 may involve prompting the user for some information which
10589 can't be obtained some other way.
10593 When using this method there are a couple of important
10594 issues which should be considered:
10598 If you discover a bug in the program which generates the
10599 configuration file, or if the format of the file changes
10600 from one version to the next, you will have to arrange for
10601 the postinst script to do something sensible - usually this
10602 will mean editing the installed configuration file to remove
10603 the problem or change the syntax. You will have to do this
10604 very carefully, since the user may have changed the file,
10605 perhaps to fix the very problem that your script is trying
10606 to deal with - you will have to detect these situations and
10607 deal with them correctly.
10611 If you do go down this route it's probably a good idea to
10612 make the program that generates the configuration file(s) a
10613 separate program in <file>/usr/sbin</file>, by convention called
10614 <file><var>package</var>config</file> and then run that if
10615 appropriate from the post-installation script. The
10616 <tt><var>package</var>config</tt> program should not
10617 unquestioningly overwrite an existing configuration - if its
10618 mode of operation is geared towards setting up a package for
10619 the first time (rather than any arbitrary reconfiguration
10620 later) you should have it check whether the configuration
10621 already exists, and require a <tt>--force</tt> flag to
10622 overwrite it.</p></sect>
10625 <appendix id="pkg-alternatives"><heading>Alternative versions of
10626 an interface - <prgn>update-alternatives</prgn> (from old
10631 When several packages all provide different versions of the
10632 same program or file it is useful to have the system select a
10633 default, but to allow the system administrator to change it
10634 and have their decisions respected.
10638 For example, there are several versions of the <prgn>vi</prgn>
10639 editor, and there is no reason to prevent all of them from
10640 being installed at once, each under their own name
10641 (<prgn>nvi</prgn>, <prgn>vim</prgn> or whatever).
10642 Nevertheless it is desirable to have the name <tt>vi</tt>
10643 refer to something, at least by default.
10647 If all the packages involved cooperate, this can be done with
10648 <prgn>update-alternatives</prgn>.
10652 Each package provides its own version under its own name, and
10653 calls <prgn>update-alternatives</prgn> in its postinst to
10654 register its version (and again in its prerm to deregister
10659 See the manpage <manref name="update-alternatives"
10660 section="8"> for details.
10664 If <prgn>update-alternatives</prgn> does not seem appropriate
10665 you may wish to consider using diversions instead.</p>
10668 <appendix id="pkg-diversions"><heading>Diversions - overriding a
10669 package's version of a file (from old Packaging Manual)
10673 It is possible to have <prgn>dpkg</prgn> not overwrite a file
10674 when it reinstalls the package it belongs to, and to have it
10675 put the file from the package somewhere else instead.
10679 This can be used locally to override a package's version of a
10680 file, or by one package to override another's version (or
10681 provide a wrapper for it).
10685 Before deciding to use a diversion, read <ref
10686 id="pkg-alternatives"> to see if you really want a diversion
10687 rather than several alternative versions of a program.
10691 There is a diversion list, which is read by <prgn>dpkg</prgn>,
10692 and updated by a special program <prgn>dpkg-divert</prgn>.
10693 Please see <manref name="dpkg-divert" section="8"> for full
10694 details of its operation.
10698 When a package wishes to divert a file from another, it should
10699 call <prgn>dpkg-divert</prgn> in its preinst to add the
10700 diversion and rename the existing file. For example,
10701 supposing that a <prgn>smailwrapper</prgn> package wishes to
10702 install a wrapper around <file>/usr/sbin/smail</file>:
10704 if [ install = "$1" ]; then
10705 dpkg-divert --package smailwrapper --add --rename \
10706 --divert /usr/sbin/smail.real /usr/sbin/smail
10708 </example> Testing <tt>$1</tt> is necessary so that the script
10709 doesn't try to add the diversion again when
10710 <prgn>smailwrapper</prgn> is upgraded. The <tt>--package
10711 smailwrapper</tt> ensures that <prgn>smailwrapper</prgn>'s
10712 copy of <file>/usr/sbin/smail</file> can bypass the diversion and
10713 get installed as the true version.
10717 The postrm has to do the reverse:
10719 if [ remove = "$1" ]; then
10720 dpkg-divert --package smailwrapper --remove --rename \
10721 --divert /usr/sbin/smail.real /usr/sbin/smail
10727 Do not attempt to divert a file which is vitally important for
10728 the system's operation - when using <prgn>dpkg-divert</prgn>
10729 there is a time, after it has been diverted but before
10730 <prgn>dpkg</prgn> has installed the new version, when the file
10731 does not exist.</p>
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